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“[Goreham and colleagues] showed quite convincingly that resistance trained individuals were more energetically ‘efficient’ and showed a number of metabolic changes with heavy resistance training that are considered to be a ‘hallmark’ of aerobic training.” Professor Stuart M. Phillips, Department of Kinesiology-Exercise Metabolism Research Group, McMaster University, Hamilton, Ontario, Canada
Strength Training Builds Endurance!
Like our article last month on the effect of “pump,” we are going to again look back on a pivotal study in exercise science. Reported in 1999, the Goreham study challenged the perceived divide between aerobic exercise and strength training. It was brought to my attention by Stuart M. Phillips, PhD, a professor of kinesiology at McMaster University in Canada. Phillips, with his colleagues, has also done research on the connection between the two forms of exercise, which we’ll be discussing in the next two articles (# 323 and 324).
Traditional thinking is that aerobic exercise increases oxygen-processing muscle components called mitochondria, and that resistance training leads to muscle hypertrophy. It has been thought that muscle gains from resistance training make you stronger, but have little or no effect on endurance; worse, weight-trained muscle is often believed to bog down endurance athletes.
Goreham and other researchers from the Kinesiology Department at the University of Waterloo (Ontario, Canada) postulated that muscle fiber hypertrophy as a result of heavy resistance training (HRT) brings with it metabolic changes characteristic of aerobic training.
To test the hypothesis, they had volunteers do strength training, and then tested their endurance on stationary bicycles. Specifically, they had untrained males, average age 20, do 12 weeks of HRT (squat, leg press and leg extension, three sets of 6-8 RM, 3 days a week). At 4, 7, and 12 weeks they examined metabolic changes using a two-stage, continuous cycling test performed at 57% and 72% of pretraining peak aerobic power (VO2max). Absolute power output and duration (about 56 minutes) remained the same; nothing was changed from test to test. The goal was to measure metabolic adaptations, if any, resulting from the resistance training. In other words, they determined whether the volunteers became more fit and better able to perform the unchanging endurance test.
Importantly, the metabolic changes measured were those generally associated with endurance training. “Regular performance of prolonged [aerobic] exercise results in a well defined series of adaptations in muscle metabolism and substrate utilization,” the researchers wrote in introducing the study. “After training, a given submaximal exercise protocol can be performed with less of a decrease in high-energy phosphate potential, less of an increase in glycogenolysis and glycolysis, and an increase in fat utilization.” (Emphasis mine)
That’s a bit technical, I know, but you get the idea. With training, metabolic adaptations occur which make the exercise easier. The researcher measured those adaptations.
Capillarization (small blood vessel formation) and mitochondrial potential also increase as a result of aerobic training. Traditional thinking is that the muscle tissue built with resistance training comes with little or no increase in capillaries and mitochondria.
Goreham et al hypothesized that muscle hypertrophy (with or without changes in capillary density and mitochondrial potential) “would result in metabolic alterations similar to those observed for prolonged exercise training.”
Heavy resistance training (HRT) did, in fact, result in metabolic adaptations usually observed during aerobic exercise. The basic hypothesis was, however, rejected, because the aerobic changes and hypertrophy didn’t come together; they came serially, one after the other.
Get ready for more physiological jargon. Here’s what they found. (It’s really quite enlightening—I promise.)
“HRT resulted in a higher phosphocreatine, a lower lactate, and a higher glycogen content,” the researcher reported. These changes, however, were observed only at the higher exercise intensity (72% VO2peak), within the first 4 weeks of training, “and before any changes in fiber cross-sectional area [hypertrophy], capillarization, or oxidative potential.”
“Additional training for a further 8 weeks failed to exaggerate the metabolic effects that were observed,” the researchers continued. “[Nevertheless], the effects of HRT on muscle exercise metabolism, at least qualitatively, are consistent with that which has been reported for prolonged exercise training.”
“As might be expected with HRT, we have not found any change in VO2peak at any stage of the training,” the researchers added. “As a consequence, the relative percent of maximal oxygen consumption used for submaximal exercise remained constant.”
Interestingly, an increase in the number of capillaries was observed at 12 weeks. “Perhaps, more importantly, the increase in capillary angiogenesis was only sufficient to offset the fiber hypertrophy, and no change in capillaries per unit fiber area was observed,” Goreham et al explained. As noted earlier, it has been thought that muscle tissue built with resistance training comes with little or no increase in capillaries. That appears to be a fallacy.
One more irregularity remained to be explained. It suggests an important strength component in some forms of endurance.
Changes occurring only during the higher-intensity cycling (72% VO2peak) may have been due in part to training specificity; HRT gains transferred to the higher-intensity cycling only. “A central factor would appear to revolve around the transfer of improvements in muscle strength, observed during the training itself, to improvements in mechanical power on the cycle, which was used to investigate the metabolic adaptations…The weight that could be lifted during 6-8 RM was measured. As expected, dramatic improvements for all three exercises occurred during the course of HRT…The improvement…translated into an increase in mechanical power output but only at the higher-resistance settings.”
There appeared to be a direct transfer of mechanical strength from resistance training to the higher intensity cycling. Again, this suggests an important strength component in some forms of endurance—in addition to the metabolic adaptations.
There’s more, but it’s too technical to explain here. (I don’t pretend to understand it all.)
Stay tuned. A bridge between aerobic and resistant exercise was starting to take shape. Rather than being polar opposites, it was beginning to look like the two forms of exercise complement one another.
We’ll tell you about the studies soon to come in the next two articles (# 323 & 324).
(The Goreham study was published in the March 1999 issue of the American Journal of Physiological Endocrinology and Metabolism.)
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