Muscle fatigue induced by a soccer match-play simulation in amateur Black South African players.

The purpose of the current study was to investigate the effects of a soccer-specific fatigue protocol on the temporal changes in torque producing abilities of the thigh within African soccer players. Twenty amateur Black South African soccer players performed the SAFT(90) soccer match-play simulation protocol, while isokinetic measurements were obtained pre-exercise (T0), after the 1st half (T45), after half time (T60) and after the 2nd half (T105). During SAFT(90) performance, significant overall concentric quadriceps peak torque changes were observed (1.05 rad · s(-1) = 16.6%, 3.14 rad · s(-1) = 9.5%). Eccentric hamstring peak torque also decreased significantly over time (1.05 rad · s(-1) = 17.4%, 3.14 rad · s(-1) = 18.5%), with significant reductions occurring during both halves. The functional strength ratio (eccH:conQ) at 3.14 rad · s(-1) was observed to significantly decrease by 10.1% overall. The indicated time-dependent changes in Black South African players have implications for competitive performance and increased predisposition to hamstring muscle injuries. Because of muscle fatigue, the hamstrings may have insufficient eccentric strength during the late swing phase when sprinting, resulting in eccentric overload and damage to the muscle. The changes in strength found in the current study help explain the increased predisposition to hamstring strains during the latter stages of both halves of match-play as reported by epidemiological studies.

Selected physiological responses during batting in a simulated cricket work bout: a pilot study.

As limited research has focused on the physiological responses associated with cricket activity, the aim of this pilot study was to measure selected physiological responses during batting in a simulated high-scoring 1-day cricket game. Ten male university cricketers performed a batting specific work bout consisting of four sprints per over (six balls) for a seven over period. Testing was conducted outdoors with players wearing full batting gear. All experimentation was conducted under temperate environmental conditions. During the simulated work bout, a portable on-line metabolic system (the k4b(2)) was attached to the subjects for the continuous assessment of selected physiological variables including heart rate (HR), ventilation (F(B), V(T) and V(E)), oxygen uptake (V(O2)) and metabolic carbon dioxide (V(CO2)) production. Energy expenditure was calculated from the oxygen consumption responses and substrate use was calculated from the V(O2)/V(CO2) responses. The results demonstrate that although the first over carried a statistically (p<0.05) lower energetic cost than the remaining six overs, most physiological responses stabilised thereafter. This excluded the heart rate responses which increased significantly (p<0.05) during the first three overs after which marginal increases were observed with no statistical difference between the last four overs (heart rate ranged from 149+/-19bt min(-1) in the fourth over to 155+/-18bt min(-1) in the last over). There was a mean energy expenditure of 2536kJh(-1) over the duration of the work bout.