Loy, S. F., Hoffmann, J. J., & Holland, G. J. (1995). Benefits and practical use of cross training in sports. Sports Medicine, 19, 1-8.

The following abstract reflects a re-interpretation of some of the points made in this extensive review.

Cross-training is usually discussed with a view to enhancing performance by posing two questions:

It is generally accepted that training effects are specific in cardiorespiratory and muscle adaptation.

With cross training, several modifying factors have to be considered.

  1. The fitness level of the individual will alter training sensitivity and the nature of effects.

  2. The amount of muscle stimulated in the cross-training activity has a moderating effect on transfer benefits. Marginal training effects in general adaptations (e.g., resting heart rate, VO2max) sometimes occur when the cross-training activity uses large muscle masses (e.g., running) and the principal activity is localized (e.g., swimming, cycling). However, transferred performance benefits in the target activity are not revealed once fitness in that activity approaches maximum. When the cross-trained muscle mass is limited, as in swimming, transfers of general adaptations or performance benefits to activities which use greater amounts of muscle are very unlikely.

  3. The intensity of training stimuli are likely to effect specific training effects in the cross-trained and target activities, each having no benefit for the other. If the intensity is sufficiently high, both forms of training will compete for the body's finite resources consequently, neither activity will be developed optimally.

  4. When the modes of training are dissimilar (e.g., cycling - a legs-dominant activity, and kayaking - an arms-dominant activity) there generally is little benefit from one activity transferred to the other unless fitness levels are low and the cross training activity uses greater muscle mass than the target activity. For elite athletes, although the research is far from comprehensive, there does not seem to be any benefit to be gained from fitness or performance improvements demonstrated in dissimilar cross-training modes.

  5. When cross-training employs similar modes of training to the target activity (e.g., rowing ergometer work with sweep-oar training) there usually is little derivable benefit once fitness reaches its ceiling level. There is every possibility that the technique features of one activity will migrate into the technique of the other and reduce skill efficiency.

    It generally is conceded that if a cyclist wants to become maximally fit then cycling is the best and only activity that will produce that state. For example, trained runners will generally have higher treadmill VO2max levels than trained cyclists.

  6. There are some potential uses for cross-training: (a) relief from boredom, (b) recovery from sport-specific injury, (c) prevention of injury, and (d) achievement of moderate levels of general fitness. Studies do support these uses but it must be remembered that only for injury rehabilitation and prevention are such activities likely to have potential use for elite athletes.

Triathlon training is not cross-training as it is used in this summary. It is more akin to training for three different sports than analogous to cross-training.

Implication. Cross-training is likely to have marginal effects on lower level, less-than-maximally-fit individuals. It is a viable prescriptive possibility for individuals interested in general fitness. However, it has no founding research for showing benefits for elite athletes, although more research is warranted. An argument could be made that cross-training has a greater potential to be detrimental to elite athlete performance than of benefit.

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