Posted April 1st, 2008
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!