Kiriakos Taxildaris

Time-course of changes in inflammatory and performance responses following a soccer game.

Objective:To study the effects of a single soccer game on indices of performance, muscle damage, and inflammation during a 6-day recovery period. Design:Participants were assigned to either an experimental group (E, played in the game; n = 14) or a control group (C, did not participate in the game; n = 10). Setting:Data were collected on a soccer field and at the Physical Education and Sports Science laboratory of the Democritus University of Thrace before and after the soccer game. Participants:Twenty-four elite male soccer players (age, 20.1 ± 0.8 years; height, 1.78 ± 0.08 m; weight, 75.2 ± 6.8 kg). Main Outcome Measurements:Muscle strength, vertical jumping, speed, DOMS, muscle swelling, leukocyte count, creatine kinase (CK), lactate dehydrogenase (LDH), C-reactive protein (CRP), cortisol, testosterone, cytokines IL-6 and IL-1b, thioburbituric acid-reactive substances (TBARS), protein carbnyls (PC), and uric acid (UA). Results:Performance deteriorated 1 to 4 days post-game. An acute-phase inflammatory response consisted of a post-game peak of leukocyte count, cytokines, and cortisol, a 24-hour peak of CRP, TBARS, and DOMS, a 48-hour peak of CK, LDH, and PC, and a 72-hour peak of uric acid. Conclusion:A single soccer game induces short-term muscle damage and marked but transient inflammatory responses. Anaerobic performance seems to deteriorate for as long as 72-hour post-game. The acute phase inflammatory response in soccer appears to follow the same pattern as in other forms of exercise. These results clearly indicate the need of sufficient recovery for elite soccer players after a game.

Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.

The present investigation attempted to determine whether resistance exercise intensity affects flexibility and strength performance in the elderly following a 6-month resistance training and detraining period. Fifty-eight healthy, inactive older men (65–78 yrs) were randomly assigned to 1 of 4 groups: a control group (C, n = 10), a low-intensity resistance training group (LI, n = 14, 40% of 1 repetition maximum [1RM]), a moderate-intensity resistance training group (MI, n = 12, 60% of 1RM), or a high-intensity resistance training group (HI, n = 14, 80% of 1RM). Subjects in exercise groups followed a 3 days per week, whole-body (10 exercises, 3 sets per exercise) protocol for 24 weeks. Training was immediately followed by a 24-week detraining period. Strength (bench and leg press 1RM) and range of motion in trunk, elbow, knee, shoulder, and hip joints were measured at baseline and during training and detraining. Resistance training increased upper-(34% in LI, 48% in MI, and 75% in HI) and lower-body strength (38% in LI, 53% in MI, and 63% in HI) in an intensity-dependent manner. Flexibility demonstrated an intensity-dependent enhancement (3–12% in LI, 6–22% in MI, and 8–28% in HI). Detraining caused significant losses in strength (70–98% in LI, 44–50% in MI, and 27–29% in HI) and flexibility (90–110% in LI, 30–71% in MI, and 23–51% in HI) in an intensity-dependent manner. Results indicate that resistance training by itself improves flexibility in the aged. However, intensities greater than 60% of 1RM are more effective in producing flexibility gains, and strength improvement with resistance training is also intensity-dependent. Detraining seems to reverse training strength and flexibility gains in the elderly in an intensity-dependent manner.

Time of sampling is crucial for measurement of cell-free plasma DNA following acute aseptic inflammation induced by exercise.

OBJECTIVES To determine the time-course changes of cell-free plasma DNA (cfDNA) following heavy exercise. METHODS cfDNA concentration, C-reactive protein levels (hs-CRP), uric acid concentration (UA), creatine kinase activity (CK) were measured before and post-exercise (immediately post, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 8h, 10h, 24h). RESULTS cfDNA increased (15-fold) 30-min post-exercise and normalized thereafter. hs-CRP increased (56%, p<0.001) 1h post-exercise, remained elevated throughout recovery (52-142%, p<0.0001), and peaked (200% rise, p<0.0001) at 24h post-exercise. UA and CK increased (p<0.05), immediately post-exercise, remained elevated throughout recovery (p<0.0001), and peaked (p<0.0001) at 24h of post-exercise recovery. CONCLUSIONS cfDNA sampling timing is crucial and a potential source of error following aseptic inflammation.

Acute exercise may exacerbate oxidative stress response in hemodialysis patients.

Background/Aims: Hemodialyzed patients (HD) demonstrate elevated oxidative stress (OXS) levels. Exercise effects on OXS response and antioxidant status of HD was investigated in the present study. Methods: Twelve HD and 12 healthy controls (HC) performed a graded exercise protocol. Blood samples, collected prior to and following exercise, were analyzed for lactate, thiobarbituric acid-reactive substances (TBARS), protein carbonyls (PC), reduced (GSH) and oxidized glutathione (GSSG), total antioxidant capacity (TAC), catalase, and glutathione peroxidase (GPX) activity. Results: HC demonstrated higher time-to-exhaustion (41%), lactate (41%) and VO2 peak (55%) levels. At rest, HD exhibited higher TBARS, PC, and catalase activity values and lower GSH, GSH/GSSG, TAC, and GPX levels. Although exercise elicited a marked change of OXS markers in both groups, these changes were more pronounced (p < 0.05) in HD patients. After adjusting for VO2 peak, differences between groups disappeared. VO2 peakwas highly correlated with GSH/GSSG, TBARS, TAC and PC at rest and after exercise. Conclusions: These results imply that HD demonstrate higher OXS levels and a lower antioxidant status than HC at rest and following exercise. Acute exercise appears to exacerbate OXS response in hemodialyzed patients probably due to diminished antioxidant defense. However, aerobic capacity level seems to be related to OXS responses in this population.