Cross training … two words that many Sports Lab locals will be familiar with, and likely shudder at, when it’s added to their rehab or training program.  I don’t know about you but when I think of cross training, I think of deep water running (or DWR for short) and admittedly I don’t have too many fond memories to reflect on. Like many in 2020 this became the year of finding alternative modes of exercise during lockdown, and for me I explored the world of DWR which prompted me to explore the current available literature on the ‘why’s’ and the ‘how’s’ of this unusual mode of exercise.   

What Is DWR?  

Sometimes after a period of running too much, too fast, for too long your body requires a break to prevent or heal from injury. I know a lot of you reading this have probably been in this situation before. But often total rest is not what is required – plus you don’t want to lose all the positive adaptations from your training efforts! And this is where DWR comes into play as an alternative mode of exercise to keep you moving as much as you can, as safely as you can, all the while proceeding on your rehab or training journey.   

DWR has steadily been gaining in popularity since the 1990’s amongst athletic and non-athletic populations, and for good reason. The work from Dr. Jack Daniels suggests that there is almost no drop in fitness if you have missed up to five days of running however, when an individual completely ceases their running program for a period longer than three weeks they will rapidly begin to lose positive training adaptations. It is also likely that these de-training effects will be greater in highly trained individuals. This is why exercise physiologists and coaches are using DWR, a weight-independent running program performed in the water with the use of a buoyancy belt (yes you are literally buoyant and running in the water) as a way to combat the effects of detraining when a period of non-weight bearing training is needed. Dr Daniels reports that amongst running populations, DWR appears to be the cross-training mode of choice over cycling or the elliptical machine due to the similarities to over-ground running in regard to motor patterning and joint range of motion, namely through the hip, knee and ankle. 

Benefits In Trained Populations  

There are many suggested benefits of DWR such as increased joint range of motion, improved muscle strength and endurance and enhanced relaxation and psychological wellbeing, as well as proposed benefits among specific medical conditions including bone stress injuries, following orthopedic surgery, arthritic conditions, fibromyalgia and lower back pain patients.  

But my biggest question when exploring the literature was ‘can DWR be an effect mode of exercise to increase aerobic fitness in athletic and non-athletic populations?’.  Amongst athletic populations more specific research is needed in this area however, of the limited available literature one study has revealed that at submaximal intensities DWR is a comparable mode of exercise to treadmill running in well trained athletes when comparing parameters such as Vo2 max, rate of perceived exertion and energy expenditure (DeMaere & Ruby 1997). Further to this, Butts, Tucker, Greenings and Smith (1990) found that when exercising at lower intensities below a heart rate of 140 BPM the metabolic costs of exercising in the water were higher compared to treadmill running at the same intensity. So, if you are a trained runner looking to take some time away from the treadmill but still wanting to improve your sub maximal aerobic fitness, DWR may be a viable alternative form of exercise to try. 

For those of you that prefer to exercise at higher maximal intensities, Reilly, Dowser & Cable (2003) concluded that DWR has lower heart rate and oxygen uptake levels and less overall cardiovascular demands when compared maximal intensity treadmill training among highly trained individuals. This may be due to the limitations of not being able to push as hard in the water compared to land-based activities. Though it has been suggested that with increased DWR experience and improved DWR mechanics these maximal values between treadmill running and DWR become more similar (Reily, Dowser & Cable, 2003). So how does this relate to you? Well, for those looking to improve anaerobic fitness at higher maximal efforts, land-based forms of exercise do appear to yield better improvements, but nevertheless DWR can be justified as an adequate stimulus for cardiovascular training.  

For injured populations, getting news that you are compelled to have 6 weeks off running is likely to get you down in the dumps, but this might just cheer you up. Eyestone, Fellingham, George and Fisher (1993) concluded that among trained endurance athletes, DWR has been found to maintain Vo2 max scores for a period of 6 weeks. After that it does appear that Vo2 max scores begin to decline rapidly, but, if you are recovering from injury its reassuring to know that with the correct programming, application, and technique of DWR you may come out of a period of training in the pool with similar aerobic fitness to when you entered it. Now that’s worth a “heck yeah!” and so is this…For those that decided to lace up recently and explore some of the beautiful running trails in Aotearoa, you are in for a treat. DWR has also been shown to alleviate lower limb muscle soreness and stiffness following intense efforts of downhill running and yields better overall lower limb physiological functioning than no active recovery methods (Takahashi, Ishihara & Aoki, 2007).  

Benefits In Untrained Populations 

And for those of you who are a more on the relaxed side of life and exercise strictly for fun, the benefits of DWR are not limited to trained populations. Research suggests that among sedentary individuals DWR has more benefit than trained populations in improving aerobic capacity (Reilly, Dowzer & Cable, 2003). Another study has shown that among untrained subjects following a 10-week aquatic resistance training program you can expect increased quadricep and hamstring strength as well as increased muscle mass (Poyonen et al., 2002). Additionally, Takeshima et al (2007) found that among older adult women there were improvements in muscle strength through leg flexion, leg extension, shoulder press, shoulder pull and back extension following a 12-week water-based training program. The strength benefits that occur are most likely due to the resistance of movement through range provided by the viscosity of the water that is approximately 800 times denser than air! So, if you are more on the sedentary side of life it appears that you will get more bang for your buck (or effort) when carrying out a DWR program compared to trained individuals.  

But, How?  

DWR can be carried out in many ways depending on skill and fitness level. The recommendation for cardiovascular training is 25 minutes five times per week, whereas for athletes, the requirements are likely to be greater. Similarly, to land-based training, interval and speed training can be carried out in the pool for sports that require rapid change of speed or direction and force application like track events and football, and for longer events like the marathon and triathlon they too can carry out lower intensity efforts in the pool, and the additions of ankle floats, arm paddles and fins can be used to increase the resistance and intensity.  For individuals returning from injury or who need a break from land-based activities, DWR is a great way to control the amount of impact and physiological stress applied to the body by reducing or increasing the depth of water the exercise is carried out in, with up to 90% of your body weight being supported when submerged in water at a depth up to your shoulders. That is a win in my books!  

Gary Killgore in 2015 reviewed the literature on DWR and recommended for runners to get the maximal transference of performance back onto the land firstly you need to use a floatation belt.  Using a floatation belt will allow you time to go through proper running biomechanics which mimic the patterns of land-based running and one way to achieve this is to have an upright posture with your trunk perpendicular to the pool floor. Not using a floatation belt will give you one heck of a workout, but likely at the expense of correct DWR mechanics. One thing to look out for when wearing a belt is to ensure you don’t lean too far forward, which many novice deep water runners will do. If you think you’re upright most likely you are still leaning forward because there is more buoyancy at the back of the belt than at the front, so if you focus on keeping your shoulders directly above your hips you should achieve a more upright posture. 

When prescribing DWR It is widely documented throughout the literature that sport specificity is key and DWR should be performed at the same intensity (or slightly higher), same duration and same frequency as your normal running training. Sorry guys there are no short cuts… your 70 minute Sunday long run will need to be carried out in full in the pool. Killgore has also stated that your perceived effort of exertion or how hard you feel you are working is slightly elevated in the pool, so it’s worthwhile to work slightly harder in the pool to get comparable rates of effort to land-based running. 

If I have swayed you to try DWR here are some personal tips to get the best out of your sessions  

  1. Find a buddy! Let’s be honest, often DWR can be tedious, particularly if you have a long session to complete, so doing it with a buddy can make it more enjoyable and keep motivation high.  
  2. Exaggerate front side mechanics (maximize hip and knee flexion) to ensure good running mechanics. Imagine that you are lifting your leg over a barrel and then rolling it behind you, this will help replicate hip flexion with the front leg and hip extension as it trails behind you.  
  3. Dorsiflex your foot (lift your toes up towards your shins), this is an action that is performed when running on land but when in the pool there is a tendency to point your toes down against the resistance of the water. Toes up! 
  4. Get into the slow lane… egos down, you will not be supersonic when DWR, in fact if you are, you likely don’t have the correct form. You will be amazed at how slow you travel in the water while at the same time working up a solid sweat session.  
  5. Keep it fresh. If you are finding your sessions become a little monotonous, change it up with some intervals, try some faster and shorter intervals broken up with short recovery periods.

So there you have it, whether you are world class athlete, a leisurely exerciser, you are coming back from injury, or you fall somewhere in-between, DWR could definitely be for you! So why not give DWR a splash!  

If you are interested in finding a local DWR facility or to see if DWR is the right form of exercise for you, don’t hesitate the contact the team at Sports Lab.  

Livvy Wilson is a SportsLab Physiotherapist who focuses on whole-body care. She is an absolute power house in her work and her sport.

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Takeshima, N, Rogers, ME, Watanabe, E, Brechure, WF, Okada, A, Yam, T, Islam, MM, and Hayano, J. Water-based exercise improves health-related aspects of fitness in older women. Med Sci Sports Exerc 34: 544–551, 2002. 

Poyohonen, T, Sipila, S, Keskinen, KL, Hautala, A, Savolainen, J, and Malkia, E. Effects of aquatic resistance training on neuromuscular performance in healthy women. Med Sci Sports Exerc 34: 2103–2109, 2002. 

Reily, T., Dowzer, C., Cable, N. (2003). The physiology od deep-water running. Journal of Sports Sciences. (12), 959-972.

Butts, N., Tucker, M., Greening, C. (1991). Physiological response to maximal treadmil and deep water running in men and women. American Journal of Sports Medicine.(19). 612-614. 

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DeMaere, JM and Ruby, BC. Effects of deep water and treadmill running on oxygen uptake and energy expenditure in seasonally trained cross country runners. J Sports Med Phys Fitness 37: 175–181, 1997. 

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Poyhonen, T, Sipila, S, Keskinen, K, Haitala, A, Savolainen, J, and Malkia, E. Effects of aquatic resistance training on neuromuscular performance of healthy women. Med Sci Sports Exerc 34: 2103–2109, 2002.