Those who are relatively new to training, or who’ve been away from the gym for an extended period of time, might not want to focus exclusively on strength or endurance exercise. A study published in the International Journal of Sports Medicine suggests incorporating both styles of training into a weekly routine can optimize muscle size, strength and endurance.

To test this theory, researchers had untrained subjects work exclusively on strength or endurance, or a combination of both for 21 weeks. The strength and endurance groups trained twice weekly, while the concurrent training subjects performed the equivalent of 4 workouts each week. They realized an 11% gain in quad muscle size compared to the 6% gains seen with strength training only. But rate of force development was greatest for subjects who trained either strength or endurance exclusively.

True Strength Moment: Turns out there’s no such thing as the perfect workout. Even though combining strength and endurance training can produce better overall results than either style alone, concurrent training still lacks something. Explosive force would have to be brought up by planning out a different program after the gains realized during 21 weeks. Of course, even those who’ve been training for years can dial in performance improvements for some aspect of their abilities. What’s your biggest weakness?