ACSM’S CERTIFIED NEWS · 2013-11-05 · ACSM’S CERTIFIED NEWS • THIRD QUARTER 2013 • VOLUME...

ACSM’S CERTIFIED

NEWST H I R D Q U A R T E R 2 0 1 3 • V O L U M E 2 3 : I S S U E 3

Online Tips and Tools Page 3

Muscle Strengthening ActivitiesPage 4

Professional and General Liability InsurancePage 6

Static StretchingPage 7

Coaching NewsPage 8

Strength TrainingPage 9

C-Reactive Protein0

ACSM’S CERTIFIED NEWSThird Quarter 2013 • Volume 23, Issue 3

In This IssueOnline Tips and Tools for Exercise Professionals: Lab Tests Online .........................................................3

Prevalence and Demographics of Muscle Strengthening Activities Among Adults in the United States .............................................................4

Professional and General Liability Insurance: When and Why You Need it .......................................6

Static Stretching in Perspective ........................................7

Coaching News ..........................................................8

Strength Training: Resistance Force and Muscle Force ..........9

A Brief Guide to C-Reactive Protein for Exercise Professionals ............................................10

Co-Editors Peter Magyari, Ph.D.

Peter Ronai, M.S., FACSM

Committee on Certification and Registry Boards Chair

Dehorah Riebe, Ph.D., FACSM

CCRB Publications Subcommittee Chair Gregory Dwyer, Ph.D., FACSM

ACSM National Center Certified News StaffNational Director of Certification

and Registry Programs Richard Cotton

Assistant Director of Certification Traci Sue Rush

Publications Manager David Brewer

Editorial Services Lori Tish

Angela Chastain

Editorial Board Chris Berger, Ph.D., CSCS

Clinton Brawner, M.S., FACSM James Churilla, Ph.D., MPH, FACSM

Ted Dreisinger, Ph.D., FACSM Avery Faigenbaum, Ed.D., FACSM

Riggs Klika, Ph.D., FACSM Tom LaFontaine, Ed.D., FACSM

Thomas Mahady, M.S. Maria Urso, Ph.D. David Verrill, M.S.

Stella Volpe, Ph.D., FACSM Jan Wallace, Ph.D.

For More Certification Resources Contact the ACSM Certification Resource Center

1-800-486-5643

Information for Subscribers Correspondence Regarding Editorial Content

Should be Addressed to: Certification & Registry Department

E-mail: [email protected] Tel.: (317) 637-9200, ext. 139 or ext. 115.

ACSM’s Certified News (issn# 1056-9677) is published quarterly by the American College of Sports Medicine Committee on Certification and Registry Boards (CCRB). All issues are published electronically and in print. The articles published in ACSM’s Certified News have been carefully reviewed, but have not been submitted for consideration as, and therefore are not, official pronouncements, policies, statements, or opinions of ACSM. Information published in ACSM’s Certified News is not necessarily the position of the American College of Sports Medicine or the Committee on Certification and Registry Boards. The purpose of the publication is to provide continuing education materials to the certified exercise and health professional and to inform these individuals about activities of ACSM and their profession. Information presented here is not intended to be information supplemental to the ACSM’s Guidelines for Exercise Testing and Prescription or the established positions of ACSM. ACSM’s Certified News is copyrighted by the American College of Sports Medicine No portion(s) of the work(s) may be reproduced without written consent from the publisher. Permission to reproduce copies of articles for noncommercial use may be obtained from the Certification Department.

ACSM National Center 401 West Michigan St., Indianapolis, IN

46202-3233 Tel.: (317) 637-9200 • Fax: (317) 634-7817 ©2013 American College of Sports Medicine.

ISSN # 1056-9677

CEPA FIRST ANNUAL MEETING

The Clinical Exercise Physiology Association (CEPA) has collaborated with the New England regional chapter of ACSM (NEACSM) to host the first Annual Meeting of CEPA. This meeting will consist of a program track developed spe-

cifically on clinical exercise physiology within the NEACSM Annual Meeting under the theme “Embracing Our Disciplines” and will be held in Providence, RI on November 14-15, 2013. The NEACSM Annual Meeting has always been a high-quality meeting, at-tracting over 900 participants annually, and the collaboration with CEPA has been carefully crafted to appeal to practicing clinicians and students alike.

Highlights of the Program• Clarkson Keynote Lecture by Paul Thompson, M.D., FACSM: “Is this Marathon Killing

Me: Cardiac Problems with Lifelong Extreme Endurance Sports”

• Steven J. Keteyian, Ph.D., FACSM: “Higher Intensity Interval Training in Patients with CVD: Swing & a Miss, or Inside-the-Park Home Run?”

• Melinda L. Irwin, Ph.D., FACSM: “Physical Activity and Cancer: Prevention & Prognosis”

• Matthew Stults-Kolehmainen, Ph.D.: “Exercise Caution when Stressed: Physical Activity Makes You Feel Good, but Does Feeling Bad Make You Less Active?”

• Deborah Riebe, Ph.D., FACSM and Randi Lite, M.A.: “Is There a Future for Exercise Professionals?”

• Peter Ronai, M.S., FACSM: “Tips & Tools for Testing and Training Fitness and Function in Older Adults”

• Clinton Brawner, M.S., FACSM: “Landmark Trials that Shaped Cardiac Rehabilita-tion… a 50 Year Perspective”

• Cathy Mullooly, M.S.: “Managing Patients with Diabetes in the Cardiopulmonary Re-habilitation Setting”

• Samuel A. Headley, Ph.D., FACSM, Richard Wood, Ph.D., and Michael Germain, M.D.: “Lifestyle Modifications in Chronic Kidney Disease (CKD): The Risk Factor Paradox”

• Edward Phillips, M.D., FACSM: “Exercise is Medicine®: Training Clinicians to Prescribe Exercise”

For more information, visit the CEPA Web site (www.acsm-cepa.org) or the NEACSM Web site (www.neacsm.org). NEACSM has applied for 13.5 CEC for this joint meeting.

2 ACSM’S CERTIFIED NEWS • THIRD QUARTER 2013 • VOLUME 23: ISSUE 3

ACSM’S CERTIFIED NEWS • THIRD QUARTER 2013 • VOLUME 23: ISSUE 3 3

Clinical Article

ONLINE TIPS AND TOOLS FOR ExERCISE PROFESSIONALS: LAB TESTS ONLINE

By Peter Ronai, M.S., FACSM, RCEP, CES, PD, CSCS-D

Health and fitness professionals can help their clients and patients obtain credible and reputable informa-tion and explanations of their medical lab tests and

results by using the Web site, Lab Tests Online.3 Lab Tests Online is developed by the American Association for Clinical Chemistry (AACC) and is peer-reviewed, non-commercial, and patient-centered.

The site recently reached its 150 millionth visitor and offered this insight “By educating patients about lab tests, Lab Tests Online strives to improve health literacy and empower patients to make informed medical decisions.” In addition, they commented “The original site receives 2 million visits per month and is used pri-marily by patients but also by health care professionals.”

Readers of ACSM’s Certified News will find the explanations of tests, their purpose(s), and meaning of results useful and can ac-cess this site at: http://labtestsonline.org/. After accessing Lab Tests Online, viewers can use the following tabs on the left-hand side of the screen:

• Understanding Your Tests: overview of understanding/ deciphering a lab report

• Inside the Lab: a behind-the-scenes explanation of lab operations

• In the News: an update of new lab test developments for specific diseases

• Article Index: index of articles, conditions, and screening recommendations

• About this Site: an explanation of the site, content, and its features

• Send Us Your Comments: a link to provide feedback to the site developers

The right-hand column of the Home page enables viewers to search three main tabs which include:

• Search box for viewers to enter a general search• Tests: an extensive index of specific lab tests• Conditions/Diseases: an extensive index of diseases and their

scope and detection • Screening: an extensive index of disease specific screening tests

and recommendations for their use

The Lab Tests Online site notes that it complies with the HON-code standard for trustworthy health information. The “Verify Compliance” link leads the viewer to their certificate, which states “The Health on the Net (HON) certificate serves as a guarantee that this website, at the date of its certification, complies with and pledges to honor the [eight] principles of the HON Code of Conduct as drawn up by the HON foundation.1” The eight principles are:

1. Authoritativeness: Indicate the qualifications of the authors2. Complementarity: Information should support, not replace,

the doctor-patient relationship3. Privacy: Respect the privacy and confidentiality of personal

data submitted to the site by the visitor4. Attribution: Cite the source(s) of published information, date

medical and health pages5. Justifiability: Site must back up claims relating to benefits and

performance6. Transparency: Accessible presentation, accurate email contact7. Financial disclosure: Identify funding sources8. Advertising policy: Clearly distinguish advertising from edi-

torial content

HON maintains that their mission is “to guide the growing com-munity of health care consumers and providers on the World Wide Web to sound, reliable medical information and expertise. In this way, HON seeks to contribute to better, more accessible and cost-effective health care”.2

Lab Tests Online also provides a mobile app of the site for iTunes, Android, and Kindle.

About the AuthorPeter Ronai, M.S., FACSM, RCEP, CES, PD, CSCS-D, is a clinical associate professor in the depart-ment of physical therapy and human movement science at Sacred Heart University in Fairfield Connecticut. He is a Fellow of the American College of Sports Medicine (ACSM).

He is Past President of the New England Chapter of ACSM (NEACSM), past member of the ACSM Reg-istered Clinical Exercise Physiologist (RCEP) Practice Board, Continuing Professional Education Committee, and current member of the ACSM Pub-lications sub-committee.

He is co-editor of ACSM’s Certified News and also the “Special Populations” column editor for the National Strength and Conditioning Association’s (NSCA) Strength and Conditioning Journal (SCJ).

References1. Health on the Net Certificate of compliance with the Code of Conduct

HONcode for Lab Tests Online [Internet]. Geneva (Switzerland): Health On the Net Foundation; [cited 2013 June 3]. Available from: https://www.healthonnet.org/HONcode/Conduct.html?HONConduct253967.

2. Health On the Net Mission [Internet]. Geneva (Switzerland): Health On the Net Foundation; [cited 2013 June 3]. Available from: http://www.hon.ch/Global/HON_mission.html.

3. Lab Tests Online [Internet]. Washington, DC: American Association for Clinical Chemistry; [cited 2013 June 3]. Available at http://labtestsonline.org.


PREVALENCE AND DEMOGRAPHICS OF MUSCLE STRENGTHENING ACTIVITIES AMONG ADULTS IN THE UNITED STATES

By Peter Magyari, Ph.D., HFS, CSCS

Muscular strength is one of the five health-related com-ponents of physical fitness.1 Activities designed to maximize improvements in muscular strength are of-

ten called resistance exercise or muscle strengthening activities (MSA). Common MSA include lifting weights (LW), calisthen-ics or bodyweight mediated exercise, and exercise with resistance bands. Free weights such as barbells, dumbbells, kettle bells, or machine weights that utilize a variety of mechanisms of resis-tance can all be characterized as MSA. The goal of health-related MSA programs should be to improve functional ability, make activities of daily living easier to accomplish, and to manage, attenuate, and even prevent debilitating health conditions (e.g., sarcopenia and osteoporosis) and chronic diseases (e.g., cardio-vascular disease, diabetes, and obesity).1

With these goals in mind, the American College of Sports Medicine (ACSM) has recommended health-related MSA be performed 2 to 3 days per week and involve each major muscle

group. But just how closely are these guidelines being followed by the average adult in the United States (U.S.)? Recently, sev-eral researchers have studied the demographic characteristics and prevalence of MSA among U.S. adults.2-3, 5-6 Depending on the survey tool utilized and the inclusiveness of activities (all MSA or just LW), estimates of U.S. adults who participate in MSA range from 6.0% to 31.7%, with those meeting the recommendation of performing MSA 2 to 3 days per week and involving each major muscle group representing the lower end of this scale.2-3, 5

When examining data from the 2009 ConsumerStyles and HealthStyles survey (N=4,271), only 31.7% reported performing MSA ≥ 2 days/wk and only 6% further reported meeting the recommendation of engaging all major muscle groups (shoulders, arms, back, chest, abdomen, legs, and hips) ≥ 2 days/wk.5 In-terestingly, there were significantly more men than women who reported performing chest, shoulder, and arm exercises while more women reported hip and leg exercises ≥ 2 days/wk. Julia Chevan studied a representative sample of 29,783 U.S. adults capable of MSA who completed the 2003 National Health In-terview Survey and found 21% reported performing MSA ≥ 2 days/wk.2

The National Health and Nutrition Examination Survey (NHANES) also provided questions related to MSA among a diverse sample of U.S. adults. In an analysis of 16,697 adults who participated between 1988 and 1994, 13.4% reported participat-ing in MSA in the previous month and 8.7% of those reported ≥ 2 days/wk.3 In a study examining the relationship between met-abolic syndrome and LW, Magyari and Churilla6 analyzed data from a fasting sub-sample (N=5,618) of adults who participat-ed in the 1999 to 2004 NHANES. They found 8.8% reported the specific MSA of LW in the previous month. Interestingly, nearly twice as many men (11.2%; 95% confidence interval [CI] 9.5, 13.1) reported LW as women (6.3%; 95% CI 5.2, 7.6) with non-Hispanic Whites (9.6%; 95% CI 8.1, 11.4) reporting the highest levels and Mexican Americans reporting the lowest levels (5.6%; 95% CI 4.4, 7.2) of engaging in this type of MSA. Ad-ditionally, higher levels of socioeconomic status were associated with greater levels of self-reported LW. Furthermore, in an ef-fort to identify if LW provided a protective effect, Magyari and Churilla found U.S. adults to be 58% less likely (p < 0.001) and 37% less likely (p < 0.01) of being diagnosed with the metabolic syndrome in the unadjusted and adjusted model for demographic variables, respectively. These findings suggest that LW may play a role in reducing the prevalence and risk of MetS among U.S. adults.

Wellness Feature


Kruger and colleagues4 analyzed data from 11,969 U.S. adults aged 50 years or older who participated in the 2001 Health In-terview Survey and found 13.7% reported performing MSA ≥ 2 days/wk. This study also found that the demographic charac-teristics of older adults who reported MSA were similar to that reported in the NHANES study that examined MSA mentioned above.6

In summarizing this information we found that in large repre-sentative samples of the U.S. adult population, between 8.7% and 21% report performing MSA ≥ 2 days/wk and as few as 6% further report meeting the recommendation of performing MSA for all major muscle groups (shoulders, arms, back, chest, abdo-men, legs, and hips) ≥ 2 days/wk. As advocates for this healthful activity, exercise professionals appear to have their work cut out in promoting MSA among U.S. adults. Additionally, this infor-mation highlights the importance of promoting the adoption of MSA and LW among subgroups of U.S. adults who underuse this valuable health promoting activity such as women, older adults, Hispanic Americans, and those of lower socioeconomic status.

Note of practical importance: Once an individual who has not previously been involved in MSA commits to begin a strengthen-ing program, it is incumbent on the exercise professional involved in the exercise program design to recognize that a relatively low resistance training stimulus is needed to initiate an adaptive

response. If initiated slowly, with a conservative model of pro-gression, MSA can be an enjoyable form of exercise that produces low levels of muscular discomfort. Improving strength should make activities of daily living easier to accomplish and prevent sarcopenia (muscle wasting). MSA will promote the building of lean tissue which should aid in managing, attenuating, and even preventing debilitating health conditions and chronic disease.1

About the AuthorPeter Magyari, Ph.D., HFS, CSCS, is an associate pro-fessor at University of North Florida and director of the Undergraduate Exercise Science Program.

References1. American College of Sports Medicine, ACSM’s

Guidelines for Exercise Testing and Prescription, (9th ED.). Philadelphia PA: Lippincott Williams and Wilkinson. p3.

2. Chevan J. Demographic determinants of participation in strength training activities among U.S. adults. J Strength Cond Res 22:553-8, 2008.

3. Galuska D, Earle D, Fulton J. The epidemiology of U.S. adults who reg-ularly engage in resistance training. Res Q Exerc Sport. 73:330-334, 2002.

4. Kruger J, Carlson S, Buchner D. How active are older americans? Prev Chronic Dis 2007 Jul. Available from: http://www.cdc.gov/pcd/is-sues/2007/jul/06_0094.htm

5. Loustalot F, Carlson S, Kruger J, Buchner D, Fulton J. Muscle-strength-ening activities and participation among adults in the United States. Res Q Exerc Sport 84:30-38, 2013.

6. Magyari P, Churilla J. Association between lifting weights and metabolic syndrome among U.S. adults: 1999-2004 national health and nutrition ex-amination survey. J Strength Cond Res 26:3113-17, 2012.

Developing the Healthy Youth Athlete:SM

The Public Health Challenge and OpportunityFebruary 11-12, 2014 Lake Buena Vista, Florida

Hosted by:

Register Today!April 1-4, 2014 Hilton Atlanta • Atlanta, GA


One aspect of ACSM’s mission is to help you become a more successful practitioner, and this involves un-derstanding and minimizing the risk inherent in

your profession.

Unless you perform services solely as a “W-2 employee” and are positive that your employer always maintains comprehensive in-surance coverage that will defend you in a lawsuit for liability damages, there is a great risk to your personal finances in not having your own liability insurance coverage.

To help you decide whether to buy professional liability and/or general liability insurance, this article provides a brief explanation of the two types of coverage and addresses situations where you may not be protected by another company’s insurance policy.

Types of CoverageProfessional Liability Insurance. This type of insurance de-fends you and pays any resulting damage awards for negligent acts, errors, or omissions in providing professional services.

Typical liability exposures for ACSM members and certified pro-fessionals arise from bodily injury claims resulting from fitness training or applied physiological services, and from providing ad-vice such as wellness and diet coaching.

General Liability Insurance. Also called “business insurance,” this type of policy defends you and pays damage awards from liability for bodily injuries that result from accidents, such as a client or guest falling on a wet floor or you accidentally dropping heavy equipment on them (but excluding injury arising directly from professional services or advice). It also covers damage you cause to others’ property.

You need general liability insurance if you work with clients at your own home or business space, at a client’s premises, at a fa-cility where you are working under the facility’s direction as an independent contractor, or at a facility where you pay a fee to use the facility. If you see your clients at your home or on their prem-ises, your homeowners or tenants liability policy likely excludes claims that arise during performance of business operations.

If you own your building and equipment, you would obtain a comprehensive insurance “package” to cover you for damage to your own property, in addition to general liability.

Coverage GapsProfessionals who provide services as a “W-2 employee” of a company or institution often assume they are covered by the em-ployer’s professional liability insurance policy. However, that is not always the case. Here are several situations in which protec-tion isn’t available:

• The employer may have an insurance gap from inadequate, un-paid, lapsed, cancelled, or already-used-up coverage.

• You may not be covered under the employer’s policy for suits filed after your employment ends.

• If a suit is based in part on your failure to comply with the em-ployer’s procedural or treatment method, the employer’s defense team may try to deflect liability to you in order to protect the employer’s own interest.

When providing services as an independent contractor under an-other trainer or facility’s direction, there’s a possibility that no other party would provide you with a defense under their insur-ance in the event you’re accused of negligence, harming someone, or damaging someone’s property. You might have to defend your-self against such allegations, unless your contractual arrangement states that the party hiring you will indemnify and defend you while you’re performing services under that party’s direction.

However, protective indemnification agreements that seem fa-vorable may not hold up in court, and could have “holes” where you would be found liable for your own actual or contributory negligence. Furthermore, the company hiring you may have in-adequate insurance at the time of a suit, or no insurance at all.

If you aren’t a “W-2 employee” but contract for services directly with clients, or are otherwise self-employed, there is no third par-ty to cover you for costs of a claim.

ACSM-Endorsed InsuranceWhether professional and/or general liability insurance is a re-quirement of your contract or just for your own peace of mind, consider the low-cost insurance plan endorsed by ACSM. This newly enhanced plan covers the professional, business, and per-sonal interests of employed or self-employed health and fitness trainers, nutrition and wellness coaches, dietitians, and students in the field.

Insurance (continued on page 13)

Wellness Article

PROFESSIONAL AND GENERAL LIABILITY INSURANCE: WHEN AND WHY YOU NEED IT

By Ronda Jones


If you are involved in sports as an athlete, a practitioner, or a lay person, you’ve likely heard or even relayed the com-ment, “stretch so you don’t get injured.” For many years, static

stretching has been considered a vital component of a proper warm-up routine.1 The postulated mechanism that is believed to provide the added benefit seems to be related to either the change in length and increased compliance of the musculotendinous unit (MTU; changes also known as elastic changes), and/or changes in the neural mechanisms through proprioceptors that have been thought to improve reactivity to changes in direction, velocity, or speeds.1, 5 Yet, many reports have claimed that static stretching may not reduce the risk of injury but actually may reduce various aspects of athletic performance. In fact, this topic became very popular with a constant flow of publications especially in the last few years. As certified professionals, we felt overwhelmed and somewhat confused and, therefore, decided to further examine this topic. This concise paper will discuss only static stretching. since it is the most common form of stretching.4 Using recent literature, we draw some guiding key points as they relate to the acute effects of static stretching on injury prevention and performance.

In the ninth edition of ACSM’s Guidelines for Exercise Testing and Prescription, published in 2013, it was stated that engaging in a stretching exercise may help prevent muscle and tendon re-lated injuries, muscle soreness following exercise, and low back pain.8 Further, it was stated that stretching exercises may lead to enhanced postural stability especially when combined with re-sistance exercises.8 Nevertheless, the scientific evidence of these benefits is mixed with some researchers demonstrating contra-dictory evidence.2, 9 The wealth of literature that deals with this broad topic may be overwhelming with a number of recent stud-ies — almost on a monthly basis — demonstrating that stretching exercises may lead to significant reductions in strength, power, and sports performance.1, 2, 4, 5, 9 Case in point, an examination of the most recently related literature (as of May 1, 2013), identified a few related articles3, 6, 7 that argue that static stretching may neg-atively affect performance. Haddad and colleagues3 demonstrated that static stretching of some major lower limb and hip muscles leads to impaired sprint and jump test performance for up to 24

STATIC STRETCHING IN PERSPECTIVEBy Meir Magal, Ph.D., FACSM, CES, CSCS and Kathleen Thomas, Ph.D., ATC, HFS

hours post exercise. Mizuno, Matsumoto, and Umemura6 argued that a total of 5 minutes (5x, 1 minute) of static stretching of the calf muscles resulted in reduced maximal voluntary contractions for up to 10 minutes. Lastly, Paradisis et al.7 demonstrated that in adolescent boys and girls, 40 seconds of static stretching of the lower limbs may lead to improved flexibility acutely but will hinder sprint and jump performances.

In an effort to clarify the most accurate approach to static stretching and its effect on injury prevention and performance, we examined three recent review articles that focused, at least in part, on the effects of static stretching.1, 4, 5 Collectively, these sys-tematic reviews used different databases to examine well over 100 different research articles. It is important to note, that the authors performed a quality analysis of each study to exclude any inap-propriate or invalid research in the review. An important word of caution noted by Behm and Chaouachi1 was that one of the biggest challenges with this topic happens to be the inconsistency displayed between the studies with respect to different factors such as: study population, randomization, reliability, methodol-ogy, and results interpretation. When reading the following key points, it is important to keep in mind that the results of the different studies that examine these topics are sometimes con-tradictory due to the reasons mentioned previously. For clarity, in some of the key points we used the adjectives “likely” and “not likely” to describe the overall direction of the literature in regards to the specific findings.

Key Points• There is likely a dose-response relationship between static

stretching and the duration of the stretch.

• The decrements in maximal strength performance that are commonly attributed to static stretching are not apparent when the duration of the stretch was < 30 seconds.

• Although some studies demonstrated a reduction in jump performance (high force production) when stretch duration was < 45 seconds, a majority of the studies did not support this finding.

• Decrements in performance are more likely when the dura-tion of the stretch is between 60 and 240 seconds.

• The majority of the studies have examined the effects of static stretching (isolated movements) on isometric and concentric performance related variables. There are only a limited number of studies that examine the effects of static stretching on eccen-tric performance related variables. This may be important since eccentric muscle action affects both performance and the risk of injury in many activities.

Health & Fitness Column

Perspective (continued on page 12)


You may have heard the phrase “coaching the whole per-son,” common in coaching parlance. How can coaches and health professionals coach ourselves and our clients

to better address our whole selves?

In July I had a hypothesis paper published entitled, “Coaching the Multiplicity of Mind: A Strengths-based Approach,”7 which offered a new model, a new perspective on the nature of our whole selves. The starting point is a set of deeply wired biologi-cal needs or capacities, that likely evolved over millions of years, such as autonomy and confidence, which scientists have recently shown as vital to our well-being. These primary needs manifest as drives and capacities, speaking to us via our inner dialogues, along with emotional and physical sensations. Sometimes they operate in conflict, or better, a healthy tension with each other. Almost everyone has the experience of one voice telling us to eat a healthy snack while another part would really prefer a brownie. We can then read our emotions as simply telling us whether our needs are met or not: negative emotions signaling unmet needs, such as more pleasure or spontaneity, while positive emotions sig-naling met needs, like the peace of mind that comes from finding meaning in a life experience.

Let’s start by coaching ourselves. Ask yourself about your cur-rent emotional status. Get out your digital or paper journal and check — which of the needs described briefly below are being met or not? Then consider what you might do to fulfill your un-met needs, improving your mood and well-being.

PRIMARy NEEdS & dRIvERS of WEll-BEING

Autonomy We have a primary need for freedom and independence. We dislike external control and can even be rebellious and resistant when we perceive that someone is telling us what we “should” or “have to” do. When we feel seduced, coerced, pressured into a behavior, we are not likely to engage in that behavior long-term. Conversely, when we have the ability to make a choice, selecting something that we find interesting or valuable, we will continue that behavior for the sake of it.2

Curiosity We have a primary need for new experiences, to explore, learn, and change. This is a very important capacity for adapting to an ever-changing world, ever curious, never taking anything for granted. We seek to be aroused and excited — even enjoying uncertainty and adventure. Psychologist and curiosity researcher Todd Kashdan6 asserts that curiosity is a primary driver of human well-being saying, “When we experience curiosity, we are willing to leave the familiar and routine and take risks, even if it makes us feel anxious and uncomfortable. Curious explorers are comfort-able with the risks of taking on new challenges. Instead of trying desperately to explain and control our world, as a curious explorer we embrace uncertainty, and see our lives as an enjoyable quest to discover, learn, and grow.”

Creativity We have a primary need to be creative, generative, imaginative, and spontaneous. It works best when our minds are unleashed to wander about, unplugged from deadlines and goals. This part of us has fun brainstorming, playing games, and being impulsive. When in full action it produces flow states — those moments where we are enjoying an activity so much that we lose track of time and execute the activity with excellence.1

ConfidenceWe have a primary need to be confident and competent. I imagine this part as the lion inside, strong and powerful. One’s sense of strength or empowerment is a key determinant of our actions — if we don’t believe we can do it, we are less likely to try it. Sometimes there is a tension with the part of us that sets the bar (discussed below), perhaps too high for our confidence levels.2

Body RegulationWe have a primary need for a healthy and calm equilibrium of our physiological systems, moving from chaos to homeostasis, over and over. We seek a balance of exertion with rest and recharge. We strive for homeostasis, stability, and a healthy autonomic ner-vous system, balancing sympathetic (stress) and parasympathetic (rest and recover) activity. Listening to one’s body’s signals tells us when it’s time to calm the nervous system, which calms the mind and improves brain function.4

Relational ConnectionWe have a primary need to love and be loved by others. This need can conflict with our need for autonomy. Throughout life, get-ting married, having children, we balance the needs for freedom and for relationships. Social psychologist Barbara Fredrickson’s exploration of the biological state of love and connection in her book Love 2.0: How Our Supreme Emotion Affects Everything We Feel, Think, Do, And Become 3 describes the capacity to create neu-ral synchrony with one another, improving brain function in the immediate term, and bettering physical health over time by im-proving the function of the hormonal, metabolic, and nervous systems. Put simply, to thrive we need to be loved and to feel we belong.7

Self-RegulationThank goodness our brains have a primary need to be orga-nized, to plan, to regulate our emotions and impulses, and keep us on track. I call this need the “executive manager,” a capable self-regulator who sets aside disruptive emotions, impulses, and distractions because of its strong desire to be productive. It is im-portant to note that our self-regulator receives a powerful boost when we exercise regularly — this is a good example of inner teamwork.

COACHING NEWS By Margaret Moore (Coach Meg), M.B.A.

Coaching (continued on page 13)


In the last two Health & Fitness columns we have respec-tively addressed physiological factors that influence muscle strength and hypertrophy, and biomechanical factors that af-

fect strength performance. As a practical application follow-up to these topics, this column will examine the relationship between resistance force and muscle force in a few standard strength train-ing exercises.

Resistance forcesThe first consideration is that the resistance force remains rela-tively constant in some exercise movements but varies widely in other exercise movements. For example, during the barbell bench press a 200-pound barbell provides essentially 200 pounds of re-sistance force at the bottom, midway, and top positions of the exercise movement. This is because the barbell action features a relatively straight vertical movement directly against the force of gravity.

However, during the dumbbell fly, 20-pound dumbbells provide different amounts of resistance force at the bottom, midway, and top positions of the exercise movement. This is due partly to the change in movement direction, and partly to the change in per-pendicular distance from the lever arm axis of rotation throughout the movement. With respect to changes in movement direction, the initial upward movement of the dumbbells is vertical, then

diagonal, and finally horizontal. Clearly, the vertical action at the beginning of the exercise movement is more challenging than the horizontal action at the end of the exercise movement (think of pushing a lawnmower up a steep incline versus pushing a lawn-mower on level ground).

With respect to changes in the lever arm perpendicular distance from the rotational axis, keep in mind that the actual resistance force is the product of the weight load times the perpendicular distance between the center of mass and the joint axis of rotation (assessed in inch-pounds). Clearly, the perpendicular distance (measured horizontally between the vertical line at the center of mass and the vertical line at the joint rotational axis) is much greater in the down position than in the up position of the dumb-bell fly exercise. For example, in the down position (upper arms horizontal) each dumbbell (center of mass) may be 20 inches away (perpendicular distance) from the shoulder joint (axis of ro-tation). Therefore, the actual resistance force to each set of prime mover muscles (pectoralis major and anterior deltoid) would be 400 inch-pounds (20 pound dumbbell x 20 inches = 400 inch-pounds). However, in the half-way up position each dumbbell (center of mass) may be only 10 inches away (perpendicular dis-tance) from the shoulder joint (axis of rotation). Therefore, the actual resistance force to each set of prime mover muscles (pec-toralis major and anterior deltoid) would be 200 inch-pounds (20-pound dumbbell x 10 inches = 200 inch-pounds). Anyone who has performed the dumbbell fly exercise, knows that the dumbbells feel much heavier in the down (upper arms horizon-tal) position and progressively lighter as they move to the up (upper arms vertical) position.

Muscle forcesAlthough vertical pressing actions provide essentially the same resistance force throughout the movement range, muscle force output varies considerably due to biomechanical factors. For ex-ample, in the barbell bench press exercise, muscle force output from concurrent horizontal shoulder flexion (pectoralis major and anterior deltoid muscles) and elbow extension (triceps muscles) is relatively low in the down position and increases progressively throughout the pressing movement. An individual who can pro-duce 200 pounds of muscle force output at the beginning of the bench press movement may be able to produce 280 pounds of muscle force output at the end of the bench press movement due to more favorable biomechanics.

Some fitness professionals believe that mechanically match-ing resistance force (called the resistance curve) to muscle force (called the strength curve) enhances strength training efficien-cy. Towards this end, most resistance machine manufacturers incorporate mechanical devices (e.g., cams, levers, linkages) that

Health & Fitness Column

STRENGTH TRAINING: RESISTANCE FORCE AND MUSCLE FORCE

By Wayne L. Westcott, Ph.D.

Resistance (continued on page 14)


overview

C-reactive protein (CRP) is a marker of inflammation in the body and has shown value as a predictor of future car-diovascular events. The usefulness of CRP as a predictor

of elevated risk for cardiovascular disease (CVD) has been well established.4 Studies have found high CRP levels to be predic-tive of myocardial infarction, stroke, peripheral arterial disease, and sudden cardiac death.8 Risk of CVD also has been shown to increase with increased sedentary behavior and decrease with participation in vigorous intensity physical activity (PA). This ar-ticle will discuss in brief 1) the discovery and production of CRP; 2) current testing methods and the corresponding risk levels; 3) effects of regular PA participation on CRP levels; and 4) a brief summary of the relationship between PA participation and CRP.

discovery and ProductionCRP was discovered in 1930 at the Rockefeller Institute for Medical Research by William S. Tillet and Thomas Francis in the serum of patients with acute inflammation due to strepto-coccus pneumonia infection.10 Initially, CRP was considered a pathogenic secretion elevated in people suffering from one of many forms of tissue damage.7 However, research has since revealed that CRP is a native protein synthesized by the liver and levels of CRP can be expected to increase in response to inflammation.

Testing MethodsLevels of this nonspecific marker of inflammation can be mea-sured using a simple blood test. Although elevated CRP levels have no perceptible symptoms, this marker of inflammation has

gained status because data from several studies has suggested that having a chronic low level of inflammation, an elevated CRP lev-el, is associated with several diseases including CVD.

Measuring an individual’s CRP level requires the use of a special-ized blood test called a high sensitivity test. This type of test has become commonplace whenever examining CRP because this test can accurately measure CRP less than 3 mg/L, levels that are used for estimating future risk. In a statement for health care pro-fessionals from the Center for Disease Control and Prevention, and the American Heart Association (AHA),6 decreased levels of CRP were associated with increased PA and endurance exercise. Using this high sensitivity CRP testing method, the AHA has recommended the following risk categories:

• low risk level, test values less than 1 mg/L • average risk level, test values between 1 mg/L and 3 mg/L • high risk level, test values exceeding 3 mg/L

CRP and PASeveral studies have revealed inverse relationships between regu-lar PA participation and CRP levels.2, 3, 5 In an analysis by Dufaux et al.,2 when the baseline CRP levels of athletes who trained at least four times per week (356 male, 103 female) were compared to those of untrained controls, the observed reductions in serum CRP level varied depending on the type of PA being reported. For example, CRP levels were significantly lower in male and female swimmers, and male rowers, when compared to those of untrained controls. However, the reductions in CRP levels were not significantly lower in female rowers or male or female soc-cer players. The authors suggested that although some training protocols, especially those requiring regular PA (such as training at least four times per week), may induce a suppressive effect on CRP levels, not all forms of training can be expected to have this effect.

Using data from the Third National Health and Nutrition Exam-ination Survey, 1988-1994, similar results have been reported when investigating PA participation and CRP. In an analysis of self-reported leisure-time PA (LTPA) and CRP, Ford reported that LTPA participation was significantly inversely associated with the CRP levels of 13,748 adults.3 Following adjustment for age, gender, race/ethnicity, education, work status, smoking, cotinine concentration (the primary metabolite of nicotine and currently considered as the best available biomarker of tobacco smoke exposure), hypertension, body mass index (BMI), waist-to-hip ratio, high-density lipoprotein cholesterol concentration, and aspirin use, the odds of having an elevated CRP concen-tration were 47% lower in participants reporting participation in vigorous PA during the previous 30 days when compared to

Clinical Column

A BRIEF GUIDE TO C-REACTIVE PROTEIN FOR ExERCISE PROFESSIONALS

By M. Ryan Richardson, BSH, MSH (2014)


a referent group reporting no LTPA. In an analysis of 4,072 adult participants of the same survey, King et al.5 examined the relationship between elevated CRP levels and various forms of exercise by comparing nonexercisers to regular exercisers. This analysis revealed significantly lower likelihood of elevated CRP among those reporting regular participation in jogging, swim-ming, cycling, aerobic dancing, calisthenics, and weight lifting. Interestingly, following adjustments for age, race/ethnicity, gen-der, BMI, smoking, and health status, this protective association remained only in those reporting jogging and aerobic dancing. The results of these two studies indicate that the reductions in odds of having an elevated CRP level may vary based on the type and intensity of PA, with more vigorous PA demonstrating a stronger beneficial association.

Gender differences in the observed protective effect of regular PA also have been reported. In a pretrial phase analysis of 1,732 male and 1,101 female participants of the Pravastatin Inflam-mation and CRP Evaluation (PRINCE) investigators reported that strenuous aerobic activity was associated with having signifi-cantly lower CRP levels in men but not women.1 The possible underlying mechanisms for the gender related differences in CRP level and participation in strenuous aerobic activity was not revealed, but these investigators hypothesized that the as-sociation may be related to lower levels of regular PA in female study participants. However, some investigators have proposed that gender differences in CRP concentrations can be explained largely by sex differences in body composition.9 These investi-gators revealed that increased adiposity was strongly associated with increased CRP in both men and in women; however, the association was much stronger in women.

SummaryLower CRP levels are associated with a reduced risk of CVD. Interest in CRP, the pathogenesis of CVD, and the possible me-diating effects of regular PA participation has increased. Some studies have revealed an inverse relationship between regular PA

participation and lower CRP levels. The mechanisms mediating this effect are not yet well defined; however, regular PA partici-pation has been shown to have a beneficial effect on CRP levels.

About the AuthorM. Ryan Richardson, BSH, MSH (2014) is a grad-uate research assistant and teaching assistant in the Department of Clinical and Applied Movement Sci-ence at University of North Florida. Mr. Richardson has presented and published abstracts presented at the World Congress on Insulin Resistance, Diabetes, and Cardiovascular Disease, the Southeast ACSM Regional Chapter, and ACSM’s Annual Meeting. Mr. Richard-son is currently completing his thesis work investigating the gender differences in muscle strengthening activity and CRP levels in U.S. adults. His previously published work includes investigations of screen time, vigorous intensity physical activity, and various markers of cardio-metabolic health.

References1. Albert MA, Glynn RJ, Ridker PM. Effect of physical activity on serum

C-reactive protein. Am J Cardiol. 2004;93(2):221-5.2. Dufaux B, Order U, Geyer H, Hollmann W. C-reactive protein serum

concentrations in well-trained athletes. Int J Sports Med. 1984;5(2):102-6.3. Ford ES. Does exercise reduce inflammation? Physical activity and C-reac-

tive protein among U.S. adults. Epidemiology. 2002;13(5):561-8.4. Jialal I, Devaraj S, Venugopal SK. C-reactive protein: risk marker or medi-

ator in atherothrombosis? Hypertension. 2004;44(1):6-11.5. King DE, Carek P, Mainous AG, 3rd, Pearson WS. Inflammatory mark-

ers and exercise: differences related to exercise type. Med Sci Sports Exerc. 2003;35(4):575-81.

6. Pearson TA, Mensah GA, Alexander RW, et al. Markers of inflammation and cardiovascular disease: application to clinical and public health prac-tice: A statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association. Circulation. 2003;107(3):499-511.

7. Pepys MB, Hirschfield GM. C-reactive protein: a critical update. J Clin Invest. 2003;111(12):1805-12.

8. Ridker PM. Clinical application of C-reactive protein for cardiovascular disease detection and prevention. Circulation. 2003;107(3):363-9.

9. Thorand B, Baumert J, Doring A, et al. Sex differences in the rela-tion of body composition to markers of inflammation. Atherosclerosis. 2006;184(1):216-24.

10. Tillett W.S., Francis T. Serological Reactions in Pneumonia with a Non-Protein Somatic Fraction of Pneumococcus. J Exp Med. 1930;52(4):561-71.

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• Different activities may require different range of motion (ROM) in various joints. In activities that require large ROM, the inclusion of a static stretching portion as part of the warm-up may be essential for a successful performance. A few examples may include the ability of a hockey goalie to maximally extend his limbs or the ability of a ballet dancer to exhibit large ROM in several joints during a routine. However, if the intended out-come of the training is to improve explosive strength/power then static stretching is not indicated (particularly for longer than 30 seconds). Be mindful of the specificity of the activity!

• The decrements in performance that are noted in the literature and related to static stretching are also likely to be related to the type of population.

• Studies that reported no change or enhanced running per-formance used either a recreational population or utilized submaximal speeds. The postulated mechanism that may lead to these results has been related to the increase in muscle compliance following acute stretching routine and, there-fore, the enhanced ability to store and use elastic energy. On the contrary, in more elite runners the acute effects of static stretching on running performance may lead to com-promised performance and is likely to be related to a reduced rate of force transmission due to reduced muscle stiffness, less than optimal crossbridge overlap, and/or changes in the length-tension relationship.

• The effects of static stretching have been shown to be related to study population. The majority of the studies that inves-tigated the acute effects of static stretching on performance used college-aged participants and the ones that used older population demonstrated mixed results. It is possible, there-fore, that similar to the recreational population (in running performance), middle aged participants may benefit from more compliant muscles (enhanced elastic properties).

• Static stretching in the general population with the intent on maintaining or improving general range of motion has been well-documented and is a very important component in providing health-related fitness benefits. As the popu-lation becomes older and less active, the lack of flexibility becomes a limiting factor for many recreational pursuits. For this population, static stretching is perfectly appropriate and recommended. For example, it is documented that in older population, the engagement in a structured intervention pro-gram that includes static stretching may improve the ROM and even reduces the risk of falling.10

• The intensity of the stretching, to the point of discomfort (POD) or below this point (<POD) seem to negatively affect subsequent performance in a similar manner.

• In regards to injury prevention, there is some evidence to show that a bout of static stretching in addition to a warm-up is not likely to reduce the risk of overuse injuries (tendonitis) but it is likely to reduce the risk of muscle strain injuries. Nevertheless, additional research is needed to test these two hypotheses.

• Most of the studies that measured the effects of static stretching on performance and injury prevention used static stretching in isolation without the other components of a formal warm-up. It is likely, therefore, that in a real world situation, where a com-plete warm-up is performed, these results may vary.

In closing, when prescribing static stretching exercise be aware of the recommended guidelines,8 the mitigating factors as mentioned earlier, and make sure to examine any new piece of literature with a grain of salt. Specifically, one needs to pay close attention to the duration of the stretch, the population (i.e. older and/or frail vs. young and/or athletic), the type of activity, and/or the nature of the injury that may be affected by the stretch.

About the AuthorsMeir Magal, Ph.D., FACSM, CES is an associate professor of Exercise Science at North Carolina Wes-leyan College. Meir has served as a member of the HFS credentialing group of ACSM’s Committee on Certifi-cations and Registry Boards (CCRB) and is currently serving as a member of the Executive Committee of CCRB.

Kathleen S. Thomas, Ph.D., ATC, HFS is an assistant professor of Exercise Science at North Carolina Wes-leyan College. Kathy has been certified as a HFS since 1990 and as an athletic trainer (ATC) by the National Athletic Trainers Association since 1991. She has pre-sented nationally and internationally on motor control/motor learning in posture and locomotion.

References1. Behm DG, Chaouachi A. A review of the acute effects of static and dy-

namic stretching on performance. European Journal of Applied Physiology. 2011;111(11):2633-51.

2. Garber CE, Blissmer B, Deschenes MR et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fit-ness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43(7):1334-59.

3. Haddad M, Dridi A, Moktar C et al. Static Stretching Can Impair Ex-plosive Performance For At Least 24 Hours. Journal of Strength and Conditioning Research/National Strength & Conditioning Association. 2013; Epub ahead of print.

4. Kay AD, Blazevich AJ. Effect of acute static stretch on maximal muscle performance: a systematic review. Med Sci Sports Exerc. 2012;44(1):154-64.

5. McHugh MP, Cosgrave CH. To stretch or not to stretch: the role of stretch-ing in injury prevention and performance. Scandinavian Journal of Medicine & Science in Sports. 2010;20(2):169-81.

6. Mizuno T, Matsumoto M, Umemura Y. Stretching-induced deficit of max-imal isometric torque is restored within 10 minutes. Journal of Strength and Conditioning Research/National Strength & Conditioning Association. 2013; Epub ahead of print.

7. Paradisis GP, Theodorou A, Pappas P, Zacharogiannis E, Skordilis E, Smirniotou A. Effects of Static and Dynamic Stretching on Sprint and Jump Performance in Boys and Girls. Journal of Strength and Conditioning Research/National Strength & Conditioning Association. 2013; Epub ahead of print.

8. Pescatello LS, American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 9th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins Health; 2013, p. p.

9. Thacker SB, Gilchrist J, Stroup DF, Kimsey CD, Jr. The impact of stretch-ing on sports injury risk: a systematic review of the literature. Med Sci Sports Exerc.. 2004;36(3):371-8.

10. Toulotte C, Fabre C, Dangremont B, Lensel G, Thevenon A. Effects of physical training on the physical capacity of frail, demented patients with a history of falling: a randomised controlled trial. Age and Ageing. 2003;32(1):67-73.

Perspective (continued from page 7)


Standard-SettingWe have a primary need for approval, appreciation, validation, and to be treated fairly, a fundamental capacity for humans, the most social animals on the planet. No man is an island, we want to be accepted by our tribes. This part of us sets the bar or stan-dard, or sets goals for our performance and then evaluates and judges that performance across all domains of life from getting good grades at school to dying well. At its worst, this capacity is difficult to please. It can be an inner critic, scanning for flaws and faults, or ever raising the bar. At its best it is accepting and content, setting the bar to challenge performance, while adopting a learning mindset when performance falls short.

Meaning-MakingWe have a primary need to find meaning and purpose in every moment, in our daily tasks, life domains, and our lives overall. We are hardwired to seek a higher purpose for our lives, to grow beyond our self-interest, and understand the “big picture” and try to figure out our place within the universe.

Mindful SelfLast and importantly our brain has the capacity to stand back from noisy inner voices and emotions, to watch the action in the brain as if watching a movie. This natural brain state allows us to be less reactive to passing emotional states, witnessing, naming, and accepting them without feeling hijacked and out of control.5 When we are in a mindful, open place we can be curious about decoding our emotional status, rather than get caught up in the frenzy.

When we are at our best, we are appreciating and valuing our primary needs and capacities, and feeling compassion for the negative emotions that come with unmet needs. We are seeking ways to meet many if not most of our needs, most of the time, supporting us to thrive and more readily meet our life’s goals and purpose.

About the AuthorMargaret Moore (Coach Meg), M.B.A., is the found-er and CEO of Wellcoaches Corporation, a strategic partner of ACSM, widely recognized as setting a gold standard for professional coaches in health care and wellness. She is co-director of the Institute of Coaching, at McLean Hospital, a Harvard Medical School affili-ate and co-directs the annual Coaching in Leadership & Healthcare Conference offered by Harvard Medical School. She co-authored the ACSM-endorsed Lip-pincott Williams & Wilkins Coaching Psychology Manual, the first coaching textbook in health care and the Harvard Health Book published by Harlequin: Organize Your Mind, Organize Your Life.

Resources1. Carson S. Your creative brain: seven steps to maximize imagination, productivi-

ty, and innovation in your life. San Francisco, CA: Jossey-Bass; 2010.2. Deci E. Why we do what we do: understanding self-motivation. New York,

NY: The Penguin Group; 1995.3. Fredrickson B. Love 2.0: how our supreme emotion affects everything we feel,

think, do and become. New York, NY: Hudson Street Press; 2013.4. Gavin J, Moore M. Body intelligence: a guide to self-attunement, IDEA

Fitness Journal, November 2010; 7(11), 42-49; http://www.ideafit.com/fit-ness-library/body-intelligence-a-guide-to

5. Kabat-Zinn J. Mindfulness for beginners: reclaiming the present moment and your life. Boulder, CO: Sounds True, Inc; 2012.

6. Kashdan T. Curious?: discover the missing ingredient to a fulfilling life. New York, NY: HarperCollins; 2009.

7. Moore M. Coaching the multiplicity of mind: a strengths-based approach. Global Adv Health Med. 2013; 2(4):78 -84.

8. Neff K. Self-compassion: stop beating yourself up and leave insecurity behind. New York, NY: HarperCollins; 2011.

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• General liability and professional liability within the same plan;• HIPAA or HITECH fines and penalties;• Limited medical expenses, regardless of fault;• Personal and advertising injury perils (libel, privacy rights,

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The policy also covers you for anyone acting under your direction or control. Refer to the actual policy language for specific terms and conditions of coverage.

To learn more about the ACSM-endorsed plan or to download an application, visit the ACSM Member & Certified profession-als Insurance Program Web site at www.ftj.com/acsm, or call ACSM’s insurance administrator, Forrest T. Jones & Company, at 1-866-820-5183. Ask for Keri Thomas at extension 1514. She can help you obtain a no-obligation rate quote on professional liability insurance.

About the AuthorSubmitted by Ronda Jones, Forrest T. Jones & Com-pany, Inc. This material is for illustrative purposes only and is intended to provide a general overview of the products and services offered. Only the policy can pro-vide the actual terms, coverages, amounts, conditions, and exclusions. Coverages, rates, and limits may differ by state.

Coaching (continued from page 8)

Insurance (continued from page 6)

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automatically vary the resistance force throughout the movement range to approximate biomechanical changes in muscle force output. For example, a chest press machine may provide 200 pounds of resistance in the starting position, progressively more resistance throughout the movement, and 280 pounds of resis-tance in the ending position.

Some strength trainers like the feel of free-weight resistance while others prefer the feel of variable resistance machines that attempt to match the resistance force to muscular force through-out the exercise movement. The research on this topic generally reveals specificity of training effects. That is, free-weight training is more effective than machine training for improving free-weight performance, and machine training is more effective than free-weight training for improving machine performance.

However, with some exercise actions appropriate changes in the resistance force may have practical application. For example, in the leg extension exercise the combination of physiological factors (e.g., muscle length) and biomechanical factors (e.g., lever-age) creates a characteristic strength curve throughout the knee extension movement range. In the example presented in the Table, you will note that the muscle force output at the begin-ning range of movement (knee flexed position) is 125 pounds. During the middle range of movement the muscle force output is higher (135 pounds to 145 pounds), and at the ending range of movement (knee extended position) the muscle force output decreases sharply to 95 pounds, 75 pounds, and 55 pounds. If the exercise resistance remains constant, it must be light enough to be lifted through the (weaker) ending range of movement. Consequently, this resistance would provide less challenge to the quadriceps muscles through the (stronger) beginning and middle phases of the movement. An appropriately designed leg exten-sion machine would vary the weight load accordingly, so that the resistance force curve would approximately parallel the muscle force curve. That is, the resistance would be proportionately higher in the stronger movement ranges and proportionately lower in the weaker movement ranges.

SummaryFree-weight exercises that move vertically (e.g., barbell bench press) provide a relatively consistent resistance force, whereas free-weight exercises that move in a curved path (e.g., dumb-bell fly) provide widely varying resistance forces throughout the movement range. Due to physiological and biomechanical fac-tors, muscle force output changes considerably throughout every resistance exercise, regardless of the movement pattern. In an attempt to parallel the resistance force curve to the muscle force curve, strength training machines typically incorporate devices that automatically vary the resistance force proportionately to muscle force potential throughout the movement range.

About the AuthorWayne L. Westcott, Ph.D., teaches Exercise Science at Quincy College in Quincy, MA.

Table. Muscle force output during maximum quadriceps contraction at different degrees of knee flexion during the leg extension exercise.

Degrees of Knee Flexion Maximum Muscle Force Output

90 Degrees 125 Pounds






Resistance (continued from page 9)

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