Cardio Timing for Fat-Burn Priming Should you do aerobics before or after your weight workout? Many prefer to do their aerobic exercise first to get it out of the way and as a general warmup. A recent study, however, suggests that the best time to do aerobics is after a weight workout and that how long you rest between the two can make a difference in both hormone release and fat oxidation.¹
Presented at the 2006 American College of Sports Medicine meeting, the study featured 10 healthy men who did three types of exercise regimens on different days:
1 Endurance exercise only (EE)
2 Endurance exercise after weight training
and a 20-minute rest (RE20)
3 Endurance exercise after weight training
and a 120-minute rest (RE120)
The weight workout consisted of six exercises, each done for three to four sets of 10 reps. The endurance exercise consisted of stationary cycling for an hour at low intensity (50 percent of maximum heart rate).
Doing the weight workout before aerobics led to marked increases in lactate, norepinephrine and growth hormone. Before the endurance exercise those in the RE120 group had the highest levels of free fatty acids in their blood, while those in the RE20 group had higher levels of norepinephrine and growth hormone. During the endurance and weight exercise, blood levels of free fatty acids and glycerol were higher in both weight groups than in the endurance-only group, meaning that those in both weight groups were burning more fat during the exercise.
The study clearly shows that doing a weight workout before aerobics leads to hormonal changes that favor increased fat oxidation during the subsequent aerobic workout.
Extend Your Sets - No Pain No Gain!
Training may induce muscular growth by promoting the release of anabolic hormones, such as growth hormone, insulinlike growth factor 1 (IGF-1) and testosterone—but it’s got to be the right kind of training. For a long time scientists have been looking for the type of training that best elicits increases in anabolic hormones. Some studies show that using a weight you can lift for 10 reps, then resting no longer than one minute between sets leads to the greatest rise in both growth hormone and testosterone. In contrast, using a weight that you can lift for only five reps and resting three minutes or more between sets results in no change in anabolic hormone release. That partly explains why many powerlifters and Olympic lifters are strong but don’t have dramatic muscle size. Scientists have found that the primary impetus for promoting the release of anabolic hormones is stress induced by the accumulation of metabolic waste produced in the muscle during exercise. Such waste includes lactate and hydrogen ions, which produce the familiar burning sensation in a muscle during an intense set. Studies also show that occlusion of blood vessels during training results in greater gains in muscle size and strength, again because of the buildup of waste products in the muscle that sends a signal to release anabolic hormones.
A recent study examined the effects of induced metabolic stress in relation to promoting gains in muscular size and strength.² Twenty-six healthy young men, average age 22, all of whom had training experience, were divided into three groups: 1) no rest, 2) with rest and 3) control. The control group didn’t exercise, but the no-rest and rest groups trained with the same exercises, using the same level of intensity. Both groups did the same routine: three sets of 10 reps of lat pulldowns, three sets of 10 reps of shoulder presses and five sets of 10 reps of leg extensions. The no-rest group, despite the name, rested one minute between sets.
While the rest group used the same routine, participants rested between the fifth and sixth rep of each set. That protocol was designed to reduce the amount of metabolic waste products that would otherwise have accumulated in their muscles during a set.
The no-rest group showed elevations of lactic acid, growth hormone and norepinephrine, while the rest group did not. Further, muscle growth occurred only in the no-rest group, with an average 13 percent increase in the muscle cross section.
Strength gains were also far greater in the no-rest group. That led the researchers to note, “The current results clearly indicate that continuous repetition without pause is an important factor for strength gains following resistance training.”
The increased acidity in muscle during intense training not only promotes anabolic hormone release but also appears to increase the level of muscle fiber recruitment. The brain apparently senses the heightened metabolic stress and compensates for it by recruiting additional fibers. More fiber recruitment translates into more muscle used, and that in turn leads to greater gains in muscular size and strength.
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