BACKGROUND:The aim of this study was to investigate the influence of excessive training on exercise performance and physiological and psychological parameters.METHODS:Eight physically active males (age, mean±standard deviation [SD]: 23±3 years) completed 3 weeks of an intervention program consisting of normal (N), intensified (IT), and recovery (R) training phases (7 days for each phase). Physiological and psychological parameters were measured at rest before the intervention (Pre), and every Monday, Wednesday, and Saturday (day 1, day 3, day 6, respectively), and exercise performance tests were performed before the intervention (Pre) and every Saturday (day 6) during the intervention period.RESULTS:The estimated energy expenditure during a training session revealed a more than two-fold increase from the N phase to the IT phase. During the IT phase, augmented training volume significantly affected the POMS (fatigue) and motivation towards training (P<0.05) scores, and these values returned to baseline levels during the R phase. Moreover, resting serum testosterone concentrations significantly decreased and exercise-induced cortisol responses were diminished during the IT phase (P<0.05). The altered endocrine responses were still observed during the subsequent R phase. Resting serum BAP levels (an index of antioxidant potential) significantly increased during the N phase (P<0.05). Meanwhile, there was no significant change in exercise performance, resting d-ROM (an index of oxidative stress) values, or salivary amylase activity.CONCLUSIONS:Increases in training stress altered psychological parameters, resting testosterone concentrations, and exercise-induced cortisol responses. Exercise performance did not correlate with training stress, suggesting that monitoring endocrine and psychological parameters is essential during intensified training periods.

This study examined the effects of different periods of hypoxic training on glucose metabolism. Sedentary subjects underwent hypoxic training (FiO2 = 15.0%) for either 2 weeks (2-week group; n = 11) or 4 weeks (4-week group; n = 10). The 2-week group conducted training sessions on 6 days week(-1) for 2 weeks, whereas the 4-week group conducted training sessions on 3 days week(-1) for 4 weeks. Body fat mass or abdominal fat area did not change after training period in either group. VO2max increased in both groups after training period (42 ± 2 versus 43 ± 2 ml min(-1) kg(-1) in 2-week group, 41 ± 1 versus 42 ± 2 ml min(-1) kg(-1) in 4-week group). Both groups showed a reduction in mean blood pressure after training period (92 ± 3 versus 90 ± 3 mmHg in 2-week group, 91 ± 2 versus 87 ± 2 mmHg in 4-week group, P ≤ 0.05). No change was observed in blood glucose response after glucose ingestion after training period. However, area under the curve for serum insulin concentrations after glucose ingestion significantly decreased in only 4-week group (6910 ± 763 versus 5812 ± 872 μIU ml(-1) 120 min, P ≤ 0.05). In conclusion, hypoxic training reduced blood pressure with independent on training duration. However, a longer period of hypoxic training led to greater improvements in insulin sensitivity compared with equivalent training over a shorter period, suggesting that hypoxic training programmes for more than 4 weeks might be more beneficial for improving insulin sensitivity.

This study determined the effects of high-intensity interval training on the exercise-induced growth hormone (GH) responses, whole body and regional fat content. Twenty-four sedentary males were randomized to either a high-intensity interval training (HIT) group or a low-intensity continuous training (LT) group. The HIT group performed intermittent exercises at 85% ofV˙O2maxOpen image in new window, whereas the LT group performed continuous exercise for 22 min at 45% ofV˙O2maxOpen image in new window. Before and after 4 weeks of training, hormonal and metabolic responses to acute exercise were determined. Acute exercise significantly increased GH concentrations in both groups (p < 0.05). However, the responses did not change after training period in either group. Furthermore, the training did not significantly affect intramyocellular or intrahepatic lipid content in either group. The present study indicates that 4 weeks of high-intensity interval training does not alter the exercise-induced GH responses, whole body fat mass or intramyocellular and intrahepatic lipid content in sedentary males.

This study compared training adaptations between once daily (SINGLE) and twice every second day (REPEATED) sprint training, with same number of training sessions. Twenty physically active males (20.9 ± 1.3 yr) were assigned randomly to the SINGLE (n = 10) or REPEATED (n = 10) group. The SINGLE group trained once per day (5 days per week) for 4 weeks (20 sessions in total). The REPEATED group conducted two consecutive training sessions on the same day, separated by a rest period of 1 h (2-3 days per week) for 4 weeks (20 sessions in total). Each training session consisted of three consecutive 30-s maximal pedalling sets with a 10-min rest between sets. Before and after the training period, the power output during two bouts of 30-s maximal pedalling, exercise duration during submaximal pedalling and resting muscle phosphocreatine (PCr) levels were evaluated. Both groups showed significant increases in peak and mean power output during the two 30-s bouts of maximal pedalling after the training period (P < 0.05). The groups showed similar increases in VO2max after the training period (P < 0.05). The REPEATED group showed a significant increase in the onset of blood lactate accumulation (OBLA) after the training period (P < 0.05), whereas no change was observed in the SINGLE group. The time to exhaustion at 90% of VO2max and muscle PCr concentration at baseline did not change significantly in either group. Sprint training twice every second day improved OBLA during endurance exercise more than the same training once daily.