The generally accepted rule is that the longer the exercise event the less emphasis on strength training, yet the role of strength training for endurance athletes remains controversial. If I dare to throw in my own two cents, I basically believe that all else being equal, a stronger athlete is a better athlete, hence I’m a strong advocate of concurrent strength and endurance training for improvement of aerobic performance.
But what does the scientific literature say about the outcome of
a program containing both aerobic and strength training? In technical
terms, this has been referred to as the interference phenomena in that
participation in one training regime diminishes the return on the
other. Numerous articles have addressed this question in past years and
various positions have emerged that can make solid conclusions
difficult. There are two points to consider in this area. First, if
power or strength is the ultimate objective (such as with power
lifters), then a combination program has been shown to inhibit ultimate
strength development. Second, what if aerobic performance is the
ultimate goal? For aerobic performance the answers are less conclusive
and while some investigators have demonstrated improved maximal oxygen
consumption from a combination program, others have not. However, to my
knowledge, and perhaps equally as important, no one has shown that it
causes a decrease in aerobic performance.
What Does the Research Say?
In general, resistance training is de-emphasized as competition
event time lengthens, i.e., the greater the aerobic demand, the less
importance is placed on resistance training. However, you should
consider that even though resistance training may have questionable
aerobic benefits, the role in injury prevention should not be
dismissed, even though it is beyond the scope of this article. For the
most part, the literature is in agreement regarding the effects of
resistance training on aerobic fitness measures. That is, there are no
real improvements unless a circuit type program is developed.
Traditional routines of 10-12 reps have not been shown to effectively
improve maximal oxygen consumption. In very untrained populations some
modest aerobic benefit may be gained.
Work by researchers assessing the effects of concurrent strength
and aerobic training in rowers demonstrated that significant
improvements could be attained using the combination program, and that
the order in which you did the resistance and aerobic exercise
mattered. In the study, three groups were used. One group lifted
weights only, while two other groups used a combination program where
one group lifted first, then rowed, and the other rowed first, then
lifted. Of the groups using a combination program, only the group who
lifted first reported a statistically significant improved VO2 max.
This certainly has implications for the frequently asked question about
the order of workouts. However, from a study design perspective, one
should be concerned that the group who rowed first did not report a
significantly improved VO2 max. (It did increase but did not reach
statistical significance.) A final interesting point in this study was
that significant improvements for VO2 were also reported for the lift
only group. A critical review of this paper identifies that the
row-lift group had significantly lower VO2 max pre-study, so this lack
of significant improvement is difficult to explain. In light of all
these findings, one consistency that emerged is that resistance
training did not compromise aerobic performance.
Additional data by other researchers showed that a training
program with an anaerobic (traditional weight lifting) design can
improve aerobic power in rowing. These investigators had athletes
perform on the rowing ergometer for three, 45-second high-intensity
work bouts, with 75 seconds of rest between bouts, and 5 minutes rest
between sets. They showed significantly improved anaerobic power and
slightly improved aerobic power on the ergometer. In the same study, a
second group displayed similar results even though they performed heavy
resistance training (2 sets of 8 reps of 10 different exercises to
failure). A final study by Pearson and Adams (2000) showed that
concurrent strength and endurance training doesn’t increase VO2 max but
does increase time to exhaustion, which is important. Equally as
important, no decrease in VO2 max was reported. This issue of improved
time to exhaustion, even though it has just sneaked in here, is crucial.
The data is sparse among other aerobic sports, but there are
some strong take-home messages. In cross-country skiing, the
predominant predictor of success in top-class athletes is upper body
strength, which clearly can be developed by both aerobic overload and
strength training. You might ask, what about VO2 max? Well, of course
VO2 max is important, but it is a requirement for high-end performance,
and among well-trained athletes it does not predict well. In the case
of cross-country skiing, upper body strength is a very potent
predictor. The data on cycling is rather contradictory, and there is
actually very little in the literature that supports using resistance
training for improved cycling performance. On a personal note, I am
disappointed to see this. For running, the data is more supportive for the inclusion of strength training.
Part of this is that the injury rates are higher in running, more so
than any other sport, and the injury reducing effects of strength
training across the board are well documented.
A perusal through the literature may leave the reader wondering
what the really true response is about concurrent training. Well, here
are the consistencies: strength improves, VO2 does not decrease, and
anaerobic power increases. This does not appear to be solid ground for
the interference phenomena! How can we explain this? My interpretation
is that for athletes who are well trained, increasing VO2 may present a
considerable challenge and may take longer than study lengths of 12
weeks. Furthermore, increasing VO2 max when it is already high is very
subject to the laws of diminishing returns and may not improve
performance, but increasing the anaerobic threshold will improve
performance. However, time to exhaustion has been shown to improve to a
greater extent than the increase in VO2 max, and this certainly is
valuable because athletes who can sustain a high output longer, will
perform better because of their greater anaerobic threshold. Therefore,
taking notice of other measures of fitness, such as strength, anaerobic
power, and time to exhaustion, can help evaluate training protocols and
improvement.
In other words don’t get pre-occupied with a high VO2 max, or a higher VO2 max.
What is important is the blend of exercises and intensities
chosen. Muscle mass can be developed (and preserved) with lower
intensity exercises. Therefore, programs should be designed to enhance
and compliment aerobic performance and not override it. Thus,
specificity is key! Choose exercises that simulate the sport movement
and specifically target those major muscles. The above presented data
also suggests that the order of including resistance training can be
influential so you might also want to consider the order in which you
perform exercises in your routine.
A final note: the reality is that for many of us, our exercise
is a means for overall health independent of the competitive piece.
With that said, for many of us our greatest functional challenge with
advancing age is loss of strength from atrophy of selected muscle
fibers. Resistance training is the most effective way to address this
loss of strength. Consider this: seniors who end up in nursing homes
often do so because of loss of strength (going up and down stairs,
opening the jar of pickles) not because they can’t run a 40-minute 10K!
So, should I lift, or not? Well, we have no evidence to suggest it will cause a decrease in athletic performance.
Of special interest to dog owners: The scientific literature on
resistance training and dogs is also sparse, although one study does
suggest that dogs who perform strength training on a regular basis are
more obedient!
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