Aquarunning – How good is aquarunning as a rehabilitation activity for sports injuries? This is what science says

When athletes get too injured to train in their usual fashion, they sometimes ‘cross-train’ in hopes of preserving fitness while they are away from their sport. Athletes who run as part of their sporting activity, but can’t train normally because of a sore knee, aching achilles tendon, painful plantar fascia, humming hamstring, etc., often turn to ‘aquarunning’ to try to stay fit. Their choice is understandable, since aquarunning seems to possess four key strong points: (1) There are no impact forces during aquarunning, damaged muscles and connective tissues are protected and often exhibit no pain during water activity; (2) Normal running form can be somewhat duplicated during aquarunning movements, so there is a reasonable hope that running-specific neuromuscular patterns of activity will be preserved and running-specific strength will be maintained, even though no ‘real’ running is being carried out; (3) High intensities of exercise can be sustained in the pool, so it’s possible that running fitness might not decline excessively during injury periods (without any training at all, an individual who runs in his/her sport can expect to lose 3 to 4 per cent of aerobic capacity within one week after stopping training – and around 15 per cent after six weeks); and (4) Great range of motion is permitted in the water; as a result, aquarunning proponents contend that flexibility and dynamic mobility may actually be enhanced during the aquatraining period.
But are any of these pro-aquarunning claims valid? Somewhat surprisingly, there has not exactly been a wealth of research concerning the merits of aquarunning. One of the few studies to explore aquarunning’s effects was carried out several years ago at Brigham Young University in the United States. There, 32 capable runners who could complete a 1.5-mile run in less than 10:45 were divided into three groups with equal levels of fitness: 10 athletes trained exclusively by running in deep water while wearing life jackets, 11 individuals trained only on exercise bicycles, and 11 other athletes continued their normal running training. All 32 of the athletes trained five times per week, 30 minutes per day, at an intensity of approximately 80 per cent of maximal heart rate (‘Effect of Water Running and Cycling on Maximum Oxygen Consumption and 2-Mile Run Performance,’ The American Journal of Sports Medicine, vol. 21(1), pp. 41-44, 1993).


Isn’t cycling as good?
After six weeks, maximal aerobic capacity (VO2max) – which by the way was measured while the athletes ran on treadmills, not while they cycled or aquaran – was absolutely equivalent between the groups, and all three collections of athletes improved average two-mile race time by about 1 per cent. In other words, the aquarunners and cyclists – even though they had taken not a single stride on Mother Earth – had upgraded their performances just as much as the runners! Several other published studies reinforce the notion that aquarunning can preserve leg strength in runners and maintain (or even raise) maximum aerobic capacity, for training periods of as long as eight weeks.
Why not cycle, though, since cycling produced the same positives (no drop in VO2max, faster race time) as aquarunning? In an interview, Utah researcher Ed Eyestone pointed out, ‘Individuals with painful quadriceps muscles, ilio-tibial-band problems, or Achilles tendinitis sometimes experience pain in those areas when they undertake cycling training.’ In contrast, there seem to be few such flare-ups during aquatraining (in fact, very few injuries to individuals who run in their sports seem to be incompatible with aquarunning).
In a separate study carried out at the University of Toledo, 11 well-trained competitive runners (10 males and one female) trained exclusively in deep water for a period of four weeks, averaging five to six workouts per week. Again, aquatraining fared very well; the athletes were able to perfectly preserve treadmill 5-K race performance (which averaged about 19 minutes flat), VO2max, and running economy, even though they completed no treadmill or regular running at all during the four-week investigation (‘Effect of 4 Weeks of deep water run training on running performance,’ Medicine and Science in Sports and Exercise, Vol. 29(5), pp. 694-9, 1997).

‘Water temperature seems to play a role, with cooler pool temperatures widening the disparity between firm-ground and water rates of cardiac beating’

Note, though, that aquarunning is not without potential problems. Running in the water may FEEL more difficult than running at the same heart rate or percent VO2max on dry land, and athletes who use heart rate to gauge the intensity of their training should be aware that max heart rate during pool running is often about 8- to 10-per cent lower, compared to normal running (‘Running on Land and in Water: Comparative Exercise Physiology,’ Medicine and Science in Sports and Exercise, vol. 24(10), pp. 1155-1160, 1992). As a result, attempts to aquarun at 85 per cent of firm-ground max heart rate might produce a scalding –
and unsustainable – intensity of approximately 95 per cent of aquarunning max. This reduction in max heart rate during aquarunning is not universal, however; some individuals may actually be able to reach higher max heart rates while running in the pool. Water temperature seems to play a role, with cooler pool temperatures widening the disparity between firm-ground and watery rates of cardiac beating.
Aside from the potential alterations in heart rate and perceived exertion, the physiology of water running is very close to that of regular dry-land rambling. In a study carried out at the University of Montana in which eight college-age male cross-country runners ran both on the treadmill and in deep water at heart rates corresponding to 60 and 80 per cent of the heart rate associated with VO2max, oxygen consumption, ventilation, and energy expenditure were identical in the two situations. The key physiological difference was that the athletes burned more carbohydrate and utilised less fat for energy when they exercised in the water (‘Effects of deep water and treadmill running on oxygen uptake and energy expenditure in seasonally trained cross country runners,’ J Sports Med Phys Fitness, Volume 37(3), pp.175-81, 1997).

Can it boost lactate threshold?
A potential bonus associated with running in the pool may be that it could spur enhancements in lactate-threshold running speed. In one study, lactate levels for well-trained runners reached a modest 2 mmol/litre during dry-land running at 75% VO2max but soared to 6-8 mmol/litre at the same intensity in the water (op cit). Assuming that normal training intensities can be attained in the pool, this should boost lactate clearance by key leg muscles and thus improve lactate threshold. Attainment of normal intensities is not automatic, however; some research indicates that working at a specific fraction of VO2max tends to feel about 20-per cent harder during aquarunning, compared with regular running. That’s why aquarunning expert Nancy Butts of the University of Wisconsin-LaCrosse in the United states recommends trying to exercise a little more strenuously than you normally do when you aquatrain.
There’s no specific information available concerning optimal body position during aquarunning. However, you should probably attempt to mimic your dry-land running form as much as possible. In addition, it may be advantageous, especially for relatively inflexible runners, to design some aquarun workouts to upgrade flexibility and mobility. To increase range of motion at the hips and stretch out taut hamstrings, aquarun expert Doug Stern of the New York Road Runners Club recommends pretending you are vaulting over hurdles – with your leading leg flexed as fully as possible at the hip and your opposite hand thrust forward to touch the lead foot (‘Deep-Water Running,’ Triathlon Today, p. 37, October-November 1992). Bear in mind, though, that no article published in a top-quality, peer-reviewed scientific journal has ever linked aquarunning with improved flexibility during regular running.
If you do decide to carry out aquarunning workouts as part of your rehabilitation, should you wear a life jacket or other flotational device to stabilise your body – or simply rely on your own muscular efforts to stay afloat (and in a running-similar posture)? Use of a vest can make aquarunning much more comfortable and at first glance might seem to help make body posture more similar to the body position associated with real running, but if you are a slim, highly trained athlete, scientific research suggests that tossing away the vest may actually spur your oxygen consumption to higher rates than would be possible with normal running, which would be a potentially positive effect. On the other hand, slipping into a flotational vest can make oxygen use 12-per cent lower during aquarunning, compared to dry-ground activity. The reason for this state of affairs is that a lot of energy during vest-free aquarunning must go into maintaining posture and keeping the body afloat, boosting oxygen-consumption rates (‘Physiological Responses to Deep-Water Running in Competitive and Non-Competitive Runners,’ Medicine and Science in Sports and Exercise, vol. 24(5), p. S23, 1992).
On the other hand, if you’re a somewhat corpulent individual, you are already attired in a subcutaneous flotation device, so it’s unlikely that vest-free running will match up with regular striding. In the study just mentioned, plumper runners were able to train at only 85 per cent of their regular (firm-ground) intensity when they did not wear vests. Nonetheless, that was better than the vested condition.

Here are a few workouts
If you or one of your clients are attempting to maintain fitness during your rehab period by carrying out aquarun training, try to complete three fairly intense workouts per week, along with two to three easy ones (the duration of the workouts should be fairly similar to your regular training times). Here are possibilities for the more frenetic sessions:
(1) Warm up by aquarunning easily for 12 minutes, and then alternate eight-minute intervals at what feels like 10-K race intensity with four- to five-minute intervals of easy aquajogging. Start with two work intervals and work up to four over time. If you don’t run 10Ks, simply use perceived exertion, shooting for 8.5 to 9 on a scale from 1 to 10, with 1 being the easiest-possible exertion and 10 being maximal.
(2) If you are a competitive distance runner, simulate a race in the pool every two to three weeks. Warm up with 12 minutes of easy aquajogging, and then work at what feels like race intensity for the typical duration of your race effort.
(3) Pretend you are in your favourite area for training, and alternate fast, heart-pounding accelerations lasting from two to five minutes with easy ‘floats’ lasting two to three minutes. Try to include some ‘pool hills’ – short, all-out blasts lasting from 20 to 40 seconds.
(4) If you are a sprinter, carry out several maximal exertions for the time duration of your sprint event per workout approximately three times per week.

Jim Bledsoe

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