Figure 4.

The impact of strength training and concurrent exercise on energy consumption. The classic Hickson (1980) study was the first to observe a decline in strength improvement and strength performance (1RM [repetition maximum] squat) over time with concurrent training (closed blue squares). The decline in strength adaptations occurred once the concurrent group was expending double the kcal/wk of the strength training only group (open circles). This suggests that the impairment in strength adaptations with concurrent exercise could reflect the role of negative energy balance on muscle hypertrophy.