Overtraning in athletes
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Transcript of Overtraning in athletes
Background
• Athletes achieve performance increase by
gradually increasing training load
• Increased loads are tolerated only through
interspersed periods of training and recovery
• If the training intensity, duration, frequency
and recovery period are not carefully
managed athletes are at risk of been
overtrained.
Epidemiology
• One study found a NFO lifetime prevalence of 60% in elite male and female runners, compared to 33% in non-elite female runners.
• A multicentre, multi-country survey found that 35% of adolescent swimmers had been overtrained at least once.
• Estimate of “staleness” were reported in 5% to 30% of swimmers over a season and in 15% of British elite athletes.
• In a recent study of elite adolescent athletes, 30% reported NFO at least once in their careers, averaging 2 episodes lasting 4 weeks.
• Risk significantly increased in individual sports, low physically demanding sports, females and elite athletes.
Symptoms of OTS
• Fatigue
• Depression
• Bradycardia
• Loss of motivation
• Insomnia
• Irritability
• Agitation
• Tachycardia
• Hypertension
• Restlessness
• Anorexia
• Weight loss
• Lack of mental concentration
• Heavy, sore, stiff muscles
• Anxiety
• Awakening unrefreshed
• Increased exercise VO2
• Decreased maximal aerobic power
• Increased basal metabolic rate
• Increased infection
Potential Triggers of OTS
• Increased training load without adequate recovery
• Monotony of training
• Excessive number of competitions
• Sleep disturbances
• Stressors including family life and occupational
• Previous illness
• Altitude exposure
• Heat injury episode
• Severe “bonk”
Glycogen Hypothesis
• Literature supports correlation between low
glycogen and decreased performance and
exercise induced fatigue
• However, no proven correlation between low
glycogen and overtrained athletes
Central Fatigue Hypothesis
Increased tryptophan
uptake in the brain
Increased serotonin and
mood symptoms
• Selective serotonin reuptake inhibitors
decreased performance
• Although, mood/fatigue are subjective and
influenced by many other factors
Glutamine Hypothesis
Decreased glutamine
Immune dysfunction
Increased susceptibility to infection
• Athletes are more susceptible to upper
respiratory tract infections after intense exercise
• However, glutamine supplementation does not
improve post-exercise impairment of immune
cells
Oxidative Stress Hypothesis
Excessive oxidative
stress
Muscle damage
and fatigue
• Resting markers of oxidative stress are higher
in overtrained athletes and increase with
exercise
• Studies on this field have been small and
there are lack of clinically relevant research
Autonomic Nervous System Hypothesis
Decreased sympathetic activation &
parasympathetic dominance
Performance inhibition, fatigue,
depression and bradycardia
• Decreased HR variability with awakening in
overtrained athletes suggest disruption of ANS
modulation
Hypothalamic Hypothesis
Dysregulation of hypothalamus and hormonal
axes
Many symptoms of OTS
• Endurance athletes have activation of HPA-
axis compared with controls
• However, other factors can influence
HPA/HPG-axis activation
• Unified theory accounting for many symptoms of
OTS and “why” it develops
• May account for many effects suggested in above
hypothesis
• In contrast, there is lack of evidence supporting
increased cytokines in overtrained athletes
• Need more research to establish the relationship
Diagnosis
• Patient history demonstrating
– Decreased performance persisting despite weeks to month
recovery
– Disturbances in mood
– Lack of sign/symptoms or diagnosis of other possible
causes for underperformance
• Screening tests
– Comprehensive metabolic panel
– FBC, ESR, C-reactive protein, iron studies, creatine kinase
– Oxidative stress biomarkers and T cell activation
– Hormonal markers
Prevention: Note to Coaches
• Periodization of training
• Tapering for competition
• Adjust training volume and intensity based on performance and mood
• Ensure adequate calorie intake and hydration
• Ensure adequate carbohydrate ingestion
• Ensure adequate sleep
• Utilize profile mood states and alter training load
• Promoting mental toughness or resilience as buffer
• Rest periods of greater than 6 hours between exercise bouts
• Avoid training following infection, heat stroke, periods of high stress
• Avoid extreme environmental conditions
Future Directions
• Future studies should involve larger number of
elite competitive athletes and observations over
longer time intervals
• Animal model of overtraining could be used to
further hypothesis testing
• Fourier transform infrared spectroscopy
• Further investigation of psychomotor speed testing
as a means of diagnosing OTS
Conclusion
• OTS is a maladapted response to excessive exercise when not matched with appropriate rest
• Many pathophysiologic hypothesis have been proposed, where cytokine hypothesis appears to be the strongest
• Differential diagnosis of FO, NFO and OTS is challenging
• Prevention is the best cure
• Further research is essential to identify definite causes and treatments
References
• Armstrong, L. & VanHeest, J. (2002). The unknown mechanism of the overtraining syndrome. Sports Medicine, 185-209.
• Hollander, D. & Meyers, M. (1995). Psychological factors associated with overtraining: Implications for youth sport coaches. Journal of Sport Behaviour, 3-19.
• Kreher, J. & Schwartz, J. (2012). Overtraining syndrome: a practical guide. Journal of Sports Health, 128-138.
• Urhausen, A. & Kindermann, W. (2002). Diagnosis of overtraining: what tools do we have? Sports Medicine, 95-102.