The interference effect states that combined strength and endurance training (i.e., concurrent training) will impair gains in either parameter due to fatigue accumulation and from the opposing qualities that each training type aims to develop. This poses a problem for coaches of virtually all team-sport athletes that require high levels of both aerobic fitness and strength/power. Program design is therefore a hot topic among these circles as all coaches are seeking to maximize both physical performance qualities with time and equipment constraints. The programming options are as follows:
a) Perform strength/power and endurance training in the same session
b) Perform strength/power and endurance training in different sessions but during the same cycle
c) Perform strength/power and endurance training in separate phases.
A recent study published ahead of print in the Journal of Strength and Conditioning Research compared the effects of option a) and b) (in addition to a strength only and control group) on explosive strength and fitness in 168 adolescent (aged 10-11 years) physical education students matched for age, height and weight. Training twice per week (separated by 2-3 days) for 8 consecutive weeks, each group performed the same workouts however a) performed strength and endurance training in the same session while b) performed them on alternating days. Before and after the 8-week training program, all subjects were tested in the 1 and 3 kg med ball throw for distance (cm), counter-movement jump, horizontal jump, 20 m sprint and predicted VO2max via 20 m shuttle run test.
The results showed that with the exception of the control group, all groups significantly improved performance on the power and speed testing variables. The strength only group failed to show any improvements in aerobic fitness. Overall, the most effective concurrent training program was b), which trained strength/power and endurance in separate sessions on alternating days. This group saw the biggest improvements in the most performance tests compared to all other groups. These results suggest that there was little interference effect with these programs in this population. It’s possible that the training volumes simply weren’t high enough to cause interference, or that the population was just too young and adaptable, having such large windows for improvement that this was not a factor. Regardless, it appears that coaches may want to perform strength/power and aerobic fitness training sessions on separate days to maximize training effects. However, given that a) saw similar improvements, combining both strength and endurance work in the same session can still be effective.
Reference:
Alves, AR. Concurrent training in prepubescent children: the effects of eight weeks of strength and aerobic training on explosive strength and VO2max. Journal of Strength and Conditioning Research. Ahead of print.
