With strength and conditioning training, it’s not just about getting the workouts in, but also when and how you get the workouts in. Developing strength, power and fitness all at the same time are common objectives for team sport athletes. Strength and power facilitate explosive movements and speed on the field and promote increases in lean body mass. On the other hand, fitness facilitates stamina on the field, promotes faster recovery between training sessions and limits injury risk by thwarting fatigue. Unfortunately, fitness and power are opposing performance qualities that require different training methods and stimulate opposing adaptations. Many coaches understand this as the interference effect where strength and power gains can be limited when too much endurance training is performed around the same time.
A new study published ahead of print in the European Journal of Applied Physiology aimed to determine the effect of concurrent power and endurance training in young physically active female subjects. The subjects were split into a power training group and a power + endurance training group. Both groups performed identical lower body resistance-based workouts aimed at developing explosive power 3 times per week for 6 weeks. However, the power + endurance group performed low intensity running for 30 minutes (60-70% of maximum heart rate) approximately 10 minutes after the resistance training session. Before and after the 6-week training period, all subjects were tested for counter-movement jump, isometric leg press force and rate of force development, half squat 1RM, vastus lateralis fiber thickness and contraction velocity as well as exercise heart rate.
The results showed that countermovement jump height (+10.7%) and peak power (+12.9%) significantly increased for the power group, but not for the power + endurance group (+3.4% and 5.1%, respectively). Isometric force and half squat 1RM improved similarly in both groups. Muscle thickness and contraction velocity improved only in the power group. Exercise heart rate was reduced in the power + endurance group, but not in the power group. The authors conclude that endurance training following power-based workouts impairs muscle growth and limits improvements in power. Therefore, schedule permitting, coaches should plan conditioning work on separate days from power training, or at the very least later in the day.
Terzis, G., Spengos, K., Methenitis, S., Aagaard, P., Karandreas, N., & Bogdanis, G. (2016). Early phase interference between low-intensity running and power training in moderately trained females. European journal of applied physiology, 116(5), 1063-1073.