H. K. A. Lakomy

Recovery of power output and muscle metabolites following 30 s of maximal sprint cycling in man.

1. The recovery of power output and muscle metabolites was examined following maximal sprint cycling exercise. Fourteen male subjects performed two 30 s cycle ergometer sprints separated by 1.5, 3 and 6 min of recovery, on three separate occasions. On a fourth occasion eight of the subjects performed only one 30 s sprint and muscle biopsies were obtained during recovery. 2. At the end of the 30 s sprint phosphocreatine (PCr) and ATP contents were 19.7 +/‐ 1.2 and 70.5 +/‐ 6.5% of the resting values (rest), respectively, while muscle lactate was 119.0 +/‐ 4.6 mmol (kg dry wt)‐1 and muscle pH was 6.72 +/‐ 0.06. During recovery, PCr increased rapidly to 65.0 +/‐ 2.8% of rest after 1.5 min, but reached only 85.5 +/‐ 3.5% of rest after 6 min of recovery. At the same time ATP and muscle pH remained low (19.5 +/‐ 0.9 mmol (kg dry wt)‐1 and 6.79 +/‐ 0.02, respectively). Modelling of the individual PCr resynthesis using a power function curve gave an average half‐time for PCr resynthesis of 56.6 +/‐ 7.3 s. 3. Recovery of peak power output (PPO), peak pedal speed (maxSp) and mean power during the initial 6 s (MPO6) of sprint 2 did not reach the control values after 6 min of rest, and occurred in parallel with the resynthesis of PCr, despite the low muscle pH. High correlations (r = 0.71‐0.86; P < 0.05) were found between the percentage resynthesis of PCr and the percentage restoration of PPO, maxSp and MPO6 after 1.5 and 3 min of recovery. No relationship was observed between muscle pH recovery and power output restoration during sprint 2 (P > 0.05). 4. These data suggest that PCr resynthesis after 30 s of maximal sprint exercise is slower than previously observed after dynamic exercise of longer duration, and PCr resynthesis is important for the recovery of power during repeated bouts of sprint exercise.

Influence of ingesting a carbohydrate-electrolyte solution on endurance capacity during intermittent, high-intensity shuttle running.

The aim of this study was to examine the effects of ingesting a carbohydrate-electrolyte solution on endurance capacity during a prolonged intermittent, high-intensity shuttle running test (PIHSRT). Nine trained male games players performed two exercise trials, 7 days apart. On each occasion, they completed 75 min exercise, comprising of five 15-min periods of intermittent running, consisting of sprinting, interspersed with periods of jogging and walking (Part A), followed by intermittent running to fatigue (Part B). The subjects were randomly allocated either a 6.9% carbohydrate-electrolyte solution (CHO) or a non-carbohydrate placebo (CON) immediately prior to exercise (5 ml kg-1 body mass) and every 15 min thereafter (2 ml kg-1 body mass). Venous blood samples were obtained at rest, during and after each PIHSRT for the determination of glucose, lactate, plasma free fatty acid, glycerol, ammonia, and serum insulin and electrolyte concentrations. During Part B, the subjects were able to continue running longer when fed CHO (CHO = 8.9 +/- 1.5 min vs CON = 6.7 +/- 1.0 min; P < 0.05) (mean +/- S.E.M.). These results show that drinking a carbohydrate-electrolyte solution improves endurance running capacity during prolonged intermittent exercise.

Effects of active recovery on power output during repeated maximal sprint cycling

AbstractThe effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output (

The hormonal responses to repetitive brief maximal exercise in humans

\bar W

The time course of the human growth hormone response to a 6 s and a 30 s cycle ergometer sprint.

) during sprint 2, compared with passive recovery [

A laboratory running test: metabolic responses of sprint and endurance trained athletes.

\bar W