Due to time and equipment constraints, coaches often hold strength workouts and conditioning workouts on the same day despite this being less than ideal as a result of the interference effect. With smaller weight rooms (or bigger teams), coaches will sometimes split the team into groups and have one group start in the weight room and the other group start on the field for conditioning, then swap. In other cases, small groups of athletes will lift at different time-slots depending on class or work schedules which may fall before or after team practices. Evidence exists indicating that conditioning work performed before strength and power training can impair performance and adaptations. However, it is unclear how various intensities of conditioning work impact subsequent strength and power performance.
A new study published in the October 2016 issue of the Journal of Strength and Conditioning Research evaluated how 4 different aerobic endurance protocols impacted resistance training performance. The sample was comprised of 11 resistance trained, college-aged males. At baseline, all subjects performed 1 RM testing and a control workout session consisting of 5 exercises (high pull, squat, bench press, dead lift and push press) with a load of 70-80% of 1RM for 6-10 repetitions. Total reps performed, barbell velocity and RPE were monitored for each set. On 4 subsequent occasions in random order, the subjects performed 1 of 4 aerobic endurance treadmill protocols (1. 60% of VO2 reserve for 45 min; 2. 75% of VO2 reserve for 20 min; 3. 90-100% of VO2 reserve for 3 min intervals with 1:1 work to rest ratio for 5 sets; 4. 75% of VO2 reserve for 20 minutes on a 6-9% incline). Ten minutes following the treadmill workouts, the subject performed the same resistance training protocol as during the control session.
The results showed that total volume was reduced between 9.1 -18.6% compared to the control session when preceded by aerobic conditioning with protocol 3 yielding the least repetitions performed followed by protocols 1, 2 and 4. Significant reductions in average power and velocity were observed following all endurance training protocols however the interval session appeared to cause the largest decrements. RPE was significantly higher following each endurance training protocol. The authors propose that the performance impairments caused by aerobic conditioning preceding resistance training workouts is likely a contributing factor to the interference effect. Therefore, if developing strength and power is a priority in training, coaches should ensure that conditioning work is not performed before resistance training workouts.
Ratamess, N. A., Kang, J., Porfido, T. M., Ismaili, C., Selamie, S., Williams, B., … & Faigenbaum, A. D. (2016). Acute Resistance Exercise Performance is Negatively Impacted by Prior Aerobic Endurance Exercise. The Journal of Strength & Conditioning Research.