Athletic training aims to increase and improve physical performance that is achieved through training overload combined with periods of rest and recovery. Overtraining syndrome (OTS) is associated with an imbalance between training and recovery. The symptoms associated with OTS vary between individuals and may reflect parasympathetic and/or sympathetic nervous system alterations as well as endocrine irregularities. The prevalence is not known, but it is usually reported among endurance athletes, such as cyclists, distance runners and triathletes. It appears that OTS represents a systemic inflammatory process with diffuse effects on the neurohormonal axis affecting host immunology and mood. Previous works, showed that cell-free DNA (cf-DNA) is correlated with the severity of excessive exercise-induced inflammation as well as with trauma and stroke severity suggesting that it might be used as a potential clinical marker for athletes with overtraining syndrome. Oxidative stress indices can be determined non-invasively and may reflect inflammatory responses after training suggesting that they could be used as clinical markers for the diagnosis of OTS. However, there are no available biomarkers to aid towards the diagnosis and/or prevention of OTS, except that of the persistence of unexplained underperformance despite an extensive recovery of the athlete. Therefore, the purpose of this study is to evaluate the potential of cf-DNA and selected oxidative stress variables as diagnostic biomarkers of OTS.
A total number of 15 elite-level runners (both male and female) and 80-100 soccer players (both male and female) will participate in the study.The day when participants (runners) will arrive at the lab early in the morning, after an overnight fast. They will have their blood pressure and orthostatic heart rate measured and they will also provide a blood sample. Immediately after participants' body composition will be assessed by dual energy X-ray absorptiometry (DXA). Then, they will perform the Meeusen test providing a second blood sample immediately after the test. During the subsequent 4-hour resting period, the participants followed by assessment of joint mobility, delayed onset of muscle soreness, flexibility and vertical jump performance after that lower limb peak torque by isokinetic dynamometer. A second Meeusen test will take place after the resting period with blood sampling post-testing. Then, participants will have a 3-hour rest, after which they will visit the lab again in order to perform the running economy testing protocol and a maximal lactate steady state test. Finally, participants will complete POMS-, quality of sleep- and symptomatology-related questionnaires and will be taught on how to complete dietary recalls. Over the subsequent 12-month period participants will provide the investigator with a detailed report of their training plan and a symptomatology questionnaire every month. These measurements take place for all participants in two different periods, in transitional period/baseline and in middle season (berore tha main race). If someone of participants manifest the symptoms of overtraining, they perform the protocol of measurements again. The day when participants (soccer players) will arrive at the lab early in the morning, after an overnight fast. They will have their blood pressure and orthostatic heart rate measured and they will also provide a blood sample. Immediately after participants' body composition will be assessed by dual energy X-ray absorptiometry (DXA). The participants followed by assessment of joint mobility, delayed onset of muscle soreness, flexibility and vertical jump performance after that lower limb peak torque by isokinetic dynamometer. After resting, they will measurement the maximum oxygen uptake in stress test on the aisle. The next days, in football players take place in field tests, will measure the Speed in 10, 30 meters, Yo-Yo IE2 (Intermittent Endurance 2), Yo-Yo IR2 (Intermittent Recovery 2) and Repeated Sprint Ability (RSA). Finally, participants (soccer players) will complete POMS-, quality of sleep- and symptomatology-related questionnaires and will be taught on how to complete dietary recalls.These measurements take place for all participants in two different periods, in transitional period/baseline and in middle season (berore tha main race). If someone of participants manifest the symptoms of overtraining, they perform the protocol again.
Study Type
OBSERVATIONAL
Enrollment
100
Athletes will be thoroughly monitored (i.e. training workload, match activities or event/race performance, markers of inflammation and oxidative stress as well as cell-free DNA) throughout the season in order to establish novel biomarkers that could function as either predictors or diagnostic tools of overtraining.
Exercise Biochemistry Laboratory, School of Physical Education & Sports Sciences, University of Thessaly
Trikala, Greece
RECRUITINGChange in cell free plasma DNA
Cell free plasma DNA will be measured with real-time PCR in plasma samples.
Time frame: At baseline, at six months and at twelve months
Change in Cortisol level
Cortisol concentration will measured in serum
Time frame: At baseline, at six months and at twelve months
Change in Testosterone level
Testosterone concentration will be measured in serum
Time frame: At baseline, at six months and at twelve months
Change in cytokine response
Concentration of TNF-α, IL-6 and IL-10 will be measured in plasma.
Time frame: At baseline, at six months and at twelve months
Change in creatine kinase in plasma
Concentration of creatine kinase will be measured in plasma
Time frame: At baseline, at six months and at twelve months
Change in uric acid in plasma
Concentration of uric acid will be measured in plasma
Time frame: At baseline, at six months and at twelve months
Change in protein carbonyls in blood
Concentration of protein carbonyls will be measured in red blood cells
Time frame: At baseline, at six months and at twelve months
Change in total antioxidant capacity
Total antioxidant capacity will be measured in plasma
Time frame: At baseline, at six months and at twelve months
Change in reduced glutathione in blood
Concentration of reduced glutathione will be measured in in red blood cells
Time frame: At baseline, at six months and at twelve months
Change in oxidized glutathione in blood
Concentration of oxidized glutathione will be measured in red blood cells
Time frame: At baseline, at six months and at twelve months
Change in catalase activity
Catalase activity will be measured in red blood cells
Time frame: At baseline, at six months and at twelve months
Change in malondialdehyde in blood
Concentration of malondialdehyde will be measured in serum
Time frame: At baseline, at six months and at twelve months
Change in blood lactate concentration
Blood lactate concentration will be measured during a maximal lactate steady-state test.
Time frame: At baseline, at six months and at twelve months
Change in peak torque
Peak torque will be assessed on an isokinetic dynamometer at 60 degrees/sec
Time frame: At baseline, at six months and at twelve months
Change in orthostatic heart rate.
Heart rate will be measured in a resting position and following 15 seconds of standing by heart rate monitor.
Time frame: At baseline, at six months and at twelve months
Change in jumping ability.
Jumping ability will be assessed by measuring squat jump.
Time frame: At baseline, at six months and at twelve months
Change in flexibility
Flexibility will be assessed through the sit and reach test.
Time frame: At baseline, at six months and at twelve months
Change in body composition.
Body composition will be assessed by dual energy X-ray absorptiometry (DXA)
Time frame: At baseline, at six months and at twelve months
Change in delay onset of muscle soreness (DOMS)
DOMS will be assessed by muscle palpation while participants are laying , standing and after performing 3 squats.
Time frame: At baseline, at six months and at twelve months
Change in complete blood count
Complete blood count analysis will be performed on an automatic blood analyzer.
Time frame: At baseline, at six months and at twelve months
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Change in RSA
5 x 30 m sprints will be performed with 25 seconds rest in-between. Mean time for 5 sprints and fatigue index will be calculated.
Time frame: At baseline, at six months and at twelve months
Change in Yo-Yo IE2
Yo-Yo IE2 will be assessed using a standardized testing protocol.
Time frame: At baseline, at six months and at twelve months
Change in Yo-Yo IR2
Yo-Yo IR2 will be assessed using a standardized testing protocol.
Time frame: At baseline, at six months and at twelve months
Change in Spreed
Spreed will be assessed using a standardized testing protocol in 10 and 30 meters.
Time frame: At baseline, at six months and at twelve months
Dietary intake
Dietary intake will be assessed using 7-day diet recalls.
Time frame: At baseline, at six months and at twelve months
Change in jumping ability.
Jumping ability will be assessed by measuring counter-movement jump.
Time frame: At baseline, at six months and at twelve months
Change in jumping ability.
Jumping ability will be assessed by measuring drop jump.
Time frame: At baseline, at six months and at twelve months