Catabolic Conclusions Researchers have arrived at contradictory conclusions concerning the effect of combining aerobic exercise and weight training. Most studies, however, show that using a program that features both types of exercise results in blunted muscular strength and size gains. The reason: Aerobics and weight training lead to physiological changes in muscle structure that more or less cancel each other out. For example, weight training leads to increased muscle contractile protein synthesis, resulting in greater strength gains. Aerobic exercise blocks that effect. Weight training doesn’t affect mitochondria, the structures in cells where energy is produced and fat is oxidized. Aerobics increases both blood delivery to muscle (providing oxygen to spark energy production) and mitochondrial activity. To develop maximum fitness and a favorable body composition, you need to do both kinds
Does bodyfat affect muscle gains?
Does having excess bodyfat adversely affect muscular gains? That was the focus of a recent study featuring 140 normal-weight and 81 overweight men and women who hadn’t trained in more than a year.1 They began training twice a week for 12 weeks, doing one-arm biceps curls. The researchers adjusted the training responses for bodyweight and initial values and found that the normalweight group had made better gains than the overweight group. That led them to conclude that there’s something about being fat that hinders muscular gains. —Jerry Brainum 1 Kelsey, B., et al. (2004). Adiposity alters muscle strength and size responses to resistance training in healthy men and women. Med Sci Sports Exerc. 36:S352.
of exercise. The question is how to incorporate aerobics with weight training without sacrificing hardearned muscle. A new study provides some hints.1 It featured 16 men who were divided into two groups, each employing a different style of aerobic exercise. One group did high-intensity interval training, characterized by alternating periods of high- and low-intensity exercise. The other group did the usual style of steady-state aerobics, using the same level of intensity throughout the workout. The aerobic sessions lasted about 40 minutes. After completing the aerobic exercise, the subjects did a weight workout consisting of bench presses and leg presses, four sets of each with a weight equal to 75 percent of their one-rep maximums. The men rested various lengths of time after the aerobics— four, eight or 24 hours. Leg press strength was compromised four and eight hours after aerobics but not 24 hours. Since the aerobics consisted of stationary cycling, only lower-body strength was affected. The study confirms conventional bodybuilding practice that training legs on the same day you do any type of aerobics affecting the leg muscles will adversely affect leg strength. The obvious solution is to wait a day after doing aerobics to train your legs. —Jerry Brainum 1 Sporer, B.C., et al. (2003). Effects of aerobic exercise on strength performance following various periods of recovery. J Strength Cond Res. 17:638-44.
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Cardio after leg training? Bad idea if you want more muscle.
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You Can’t Flex Fat
When to do aerobics so you don’t lose muscle
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