For Top Athletes, Strength and Endurance Training May Clash
WebMD News Archive
Jan. 20, 2000 (Atlanta) -- Optimal fitness seekers must decide if their #1
goal is strength or endurance. According to Michael Leveritt, PhD, from the
Centre for Sport and Exercise Science at Waikato Polytechnic in Hamilton, New
Zealand, if it's strength they're after, they should skip the running. Those
who train for both types of fitness will probably be disappointed.
"Strength gains during combined strength and endurance training are not
likely to be as great when compared with strength gains achieved through
strength training alone," Leveritt tells WebMD.
For his report, which appears in the December issue of Sports
Medicine, Leveritt studied previous research that looked at concurrent
training. Although he says that the comparisons were often difficult because of
varying study methods and fitness levels of participants, one overriding
principle did emerge: Increases in strength will suffer if endurance exercise
is attempted at the same time.
Not only are the physiological effects from strength or resistance and
endurance training different, says Leveritt, but sometimes they may even be
opposite. He cites numerous studies that show endurance training contributing
to a loss in strength and decreased muscle-fiber size. "What might be
happening," he tells WebMD, "is that when individuals perform a bout of
strength training after they have done some endurance training -- even on the
preceding day -- the quality of training and/or the physiological response to
the strength training may be less than optimal." He notes, on the other
hand, that he discovered instances in which resistance training can cause an
increase in both.
According to Leveritt, running seems to have the greatest negative effect on
strength when combined with training geared towards building strength. He found
inconsistent results when cycling was studied. The two exercises that have the
least negative effect on strength are endurance rowing and hand cranking.
The probable reasons given by Leveritt for combination training's negative
effect on strength include:
- contrasting effect on muscle fibers of the various exercises.
- differences in hormonal needs for both types of exercise.
- differences in demands placed on the neuromuscular system during endurance
and strength training.
- differences in level and type of fatigue. "There is evidence to suggest
that residual fatigue from a bout of prior endurance exercise inhibits the
quality of subsequent strength exercise," writes Leveritt.