TrainingThe Science of Performance |
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Cross Training for Runners
One of the more controversial recommendations that I make is that runners of average genetic talent should not run the high volumes or frequencies so often recommended by conventional training wisdom. Generally speaking, for runners with average genetic talent I suggested 2-3 days per week of running, 1-2 days per week of cross training, and 1-2 days per week of strength training. While 2-3 days per week of running seems small when compared to the volume of training recommended by modern training theory, when combined with cross training and strength training the volume of training that I recommend more closely resembles that of conventional training. Since I basically recommend 4-6 training days per week, why not run each of those training days instead of the 2-3 that I recommend? Doesn’t the principle of specificity teach us that nothing is better for running than running? Can cross training lead to the same performance improvements as run only training? This is the topic we will be examining today. Research There have been several research studies examining the effect of cross training on performance. For our purposes, we will examine two studies that specifically examined the effect of cross training on run performance. Mutton and colleagues compared the effects of run only vs. combined cycling and running on running performance of 11 moderately trained runner (1) and Flynn and colleagues compared run only to cycle/run training in 20 well-trained competitive runners (2). Let’s take a close look at these two studies. Mutton and co-workers recruited 11 moderated trained runners in order to investigate the effects of 5 weeks of high intensity cross training to a similar intensity run only training program. The subjects were averaging 16-30 km weekly run training prior to beginning this study and their average 5k run time was 23 minutes. Though these subjects have running experience, they would not be considered to be highly trained runners. The subjects were pair matched for initial 5k run performance and then randomly assigned to either a run only group (6 subjects) or a cross trained group (5 subjects). The run only group ran 4 days per week, 45 minutes per session. The cross trained group ran 2 days per week and cycled on an ergometer 2 days per week, 45 minutes for each session. No other training was performed by the subjects during the study period. Training intensity was the same for both groups; initial intensity was set at 80-85% of max heart rate (maxHR) and was increased to 85-90% maxHR during weeks 2-5 for continuous training. Intervals at 95% maxHR or greater were added in weeks 3-5, beginning with 60 sec intervals and peaking at 90 sec intervals during week 5. In the second research study, Flynn and co-workers recruited 20 well trained competitive runners to examine the effects of 6 weeks increased training via cross training or run only training. The subjects in this study were required to have trained for at least 32 km per week for the previous 6 months and to be currently competing at 5, 10, or 42 km distances. As it turned out, prior to the start of the study the average weekly training distance for these subjects was 50 km per week (+/- 13.9 km per week) and they averaged 18:16 min:sec in the 5k. They also had an average VO2max of about 64 ml/kg/min. These subjects would be considered high caliber runners. In addition to the 20 training subjects, 10 age-matched recreationally active subjects were recruited as a control group. The training subjects were matched for age, training volume, and aerobic capacity and then randomly assigned to either a run only group or a cross training group. The subjects were asked to maintain their normal running distance and intensity for 6 weeks while reporting to the testing lab Mondays, Wednesdays, and Fridays for 3 additional training sessions per week. Mondays’ workout consisted of 5 sets of 5 minutes work at 95% of VO2peak. Wednesdays’ workout consisted of 50-60 minutes at 70% of VO2peak, and Fridays’ workouts consisted of 3x2.5 min at 105% of VO2peak and 6x1.5 min at 115% VO2peak. The run only group completed Monday and Friday workouts on a 400m outdoor track and Wednesday workouts on a measured road course. The cross training group completed all their additional training on a cycle ergometer. All the subjects kept individual training logs of all their training sessions – normal and additional. Results What were the results of these two research studies? In both cases there was no difference in performance between the run only groups and the cross trained groups. In the study by Mutton of moderately trained runners, 5km time improved for the run only group and cross trained group by 7.3% and 7.5% respectively. The run only group improved from an average of 23:18 to 21:36 while the cross trained group improved from 22:42 to 21:00. There was no significant difference in performance between the two groups in any of the measured physiological or performance variables. In the study by Flynn of the 20 high caliber runners, 5km run time improved significantly and equally for both the run only and cross training groups. 5km run time decreased on average from 18:16 to 17:48, a 28 second improvement, with no significant difference in improvement between the two groups. Table 1: improvement in 5k performance pre and post study
* estimated time from figure 3 in the research article – exact times not provided Discussion The most obvious conclusion we can draw from these two studies is that cross training is equally as effective as additional run training at improving run performance. However, we should explore this in greater detail before we accept the most obvious conclusion as being correct. First, note that the studies used subjects with different training backgrounds. It can be difficult to generalize the results of a study on a particular group (untrained subjects for example) to all other groups (well trained or elite runners for example). Even though the lesser trained groups improve quite a bit more than the higher caliber groups – 1:42 improvement vs. 28 sec. – the fact that both groups improved significantly supports the idea that cross training can be valuable for all runners. Second, note that both studies used cycling as the method of cross training. Cycling, while obviously different from running, does use the same basic muscle groups as running. Would the subjects have experienced the same level of improvement if they had cross trained using different muscle groups? Perhaps not; another research study compared improvements in running between a run only and a combined run/swim group. While this study note improvements in both groups, there was a significantly greater improvement in the run only group (3). Our conclusion from this can be that improvements in general fitness can lead to specific performance improvements, but that the cross training employing the same basic muscle groups is likely to lead to greater improvements. Third, note the high level of intensity employed in both studies. Both studies added high intensity training to the training programs of the subjects. It’s a well known and accepted fact that the addition of high intensity training causes significant improvements in performance. The really interesting thing about these studies is that it mattered not whether the additional high intensity training consisted of running or cycling; in either case, performance improved. This adds additional evidence to the idea that it is intensity that is most responsible for improvements in performance. You might make the case that overall training volume increased for both groups, irrespective of training intensity, and that the increase in training volume also contributed to the improved performance enjoyed by all the subjects. True, an increase in overall training volume could possibly explain the results from these two studies. However, when we compare the results of these two studies to the results of the study on cross country skiers (base building vs. high intensity article) we note that a significant increase in training volume with no increase in intensity resulted in no improvement in performance for the skiers. Additionally, research on strength training - and strength training could easily be considered high intensity cross training - shows improvements in endurance performance from the addition of strength training. These comparisons support the idea that intensity plays a more significant role in performance than does volume – even when volume is specific to the activity being performed and intensity is added via cross training. Lastly, neither of these two studies resulted in overtraining or injury (though Mutton’s study had the twelfth subject withdraw due to a pre-existing injury). Summary The conclusion that we can draw from these studies is that high intensity cross training that involves the same basic muscle groups as running is likely to be as effective as run only training for improving performance. Reference:
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