Melis “Mel” Edwards, MS, creator of the H.I.T. Method™ (Hydrofit Interval Training), has spent the past 20 years promoting water fitness training both for athletes and as an athlete herself. Edwards, group fitness instructor and director of admissions at Montana State University in Bozeman, Montana, has trained both professional and recreational athletes.

Case in point, Kelcie Nice, a 33-year-old Ironman® athlete and resource engineer, was training for her first Ironman when she developed a hip imbalance. Nice discovered Edwards and trained entirely in the water for 2 months until the problem was corrected. For the next 4 months until the race, she continued hydrotraining 2—3 times per week. “I’m now a lifetime proponent of water running and walking proof that it is not only a legitimate alternative to land running but could possibly even be the way to go,” she says. “There’s no doubt that [land] running, with the constant impact it delivers, is not easy on the body, no matter how addicting those endorphins may be.”

Water fitness has come a long way from its origin story of older women in shower caps having fun in the local pool. Ken Baldwin, director of education at Perform Better Australia, in Brisbane, says, “In Australia, aqua is the ‘go–to’ method of recovery for all Australian Football Rules teams—rugby and soccer. If they can’t get to a cold-water beach, they’ll go to an ice pool to do their walking and regeneration and recovery moves. All professional sporting teams are using water training from that perspective.” Experts agree that interest in deep water running and aquatic boot camp is increasing.

This article examines what’s new in aquatic training research, what’s changing in water fitness class demographics and which program trends are growing. Higher-intensity training and recovery continue to be popular throughout the fitness industry, and aquatic exercise provides options for both. If you’re looking to expand your training repertoire, check out this new wave of possibilities.

Research Update

Mounting research on the benefits of aquatic exercise is changing its image and supporting the claim that it helps people of all ages and ability levels. Before diving into the research, it’s good to review why water is a complementary training medium to weight-bearing, land-based activities. For more on this, see the sidebar “The Properties of Water.”

The gold standard in research is the randomized controlled trial, but owing to lack of funding, few such trials exist in aquatic research, according to experts. Mary E. Sanders, PhD, FACSM, adjunct professor/specialist in internal medicine at the University of Nevada, Reno, school of medicine, and adjunct professor at the university’s school of community health sciences, says, “Many of us would like to see [research] protocols described better by investigators, with more emphasis on studies that extend for longer periods of time… If a study is published in a scientific journal or presented at a scientific meeting with peer review, then it needs to be considered. Many studies have low numbers of exercisers, examine unrealistic exercises or do not take into consideration the properties of water, which perhaps may have changed their conclusions.”

Here are some of the newer findings related to aquatic training, as identified by researchers involved in peer-reviewed studies.

Aquatic training improves ability to perform activities of daily living (ADL). The effectiveness of functional aquatic training for older adults seems well-established. Older women who participated in 60–minute shallow–water exercise classes 3 days a week for 12 weeks performed better in land-based ADL, but did not improve balance (Sanders et al. 2016). The Golden Waves® program, used in this and other studies, has proved effective in all variables except for balance, which has had inconsistent results. Sanders notes that for balance improvement, water depth is critical and shallower is better. “When water is armpit depth, it seems there’s not enough gravity ground-force reaction to challenge balance somatosensory systems (feet),” she says. See the “Resources” sidebar for additional information.

Water fitness enhances muscular strength and endurance, and increases lean body mass. Evidence shows that people of all ages and ability levels can improve strength, endurance and body composition through effective aquatic training. Postmenopausal women who trained with aquatic resistance equipment twice a week for 10 weeks gained strength, reduced fat and increased lean body mass as effectively as women who used weight machines and exercise bands in equivalent land programs (Colado et al. 2012).

Fit young men who did a periodized strength training program 3 times a week for 12 weeks significantly improved muscular strength and power and increased lean body mass (Colado et al. 2009). Healthy, untrained older women who did 60 minutes of shallow–water exercise (including 20 minutes of upper- and lower-body resistance training with equipment) 3 days a week for 24 weeks increased lean body mass by 3.4% and significantly improved muscular strength (Tsourlou et al. 2006).

Water exercise can meet cardiovascular fitness metrics. New research is settling the debate about whether upright water training is an effective way to cross-rain for better cardiovascular fitness. Sanders points to recent research (she was a co-author) that showed that cardiovascular training in water is effective when appropriate protocols, speed and movements are employed. Unskilled healthy young women met ACSM ranges for cardiovascular training in a 40-minute shallow–water session while using resistance gloves. The “hover jog” achieved the greatest average intensity, at 7.3 METs (Nagle et al. 2013).

There’s a correlation between rating of perceived exertion and cardio variables. The properties of water affect heart rate. If you compare water training with land training at the same intensity, heart rate may be as much as 20% lower in the water and will vary from person to person (Haff 2008). Findings from multiple studies in both deep water and shallow water show a significant correlation between overall RPE and cardiorespiratory and neuromuscular variables (Pinto et al. 2015). For some people, RPE may be higher because they use anaerobic energy systems to power their arms and legs through water. Researchers note that it’s important to introduce and explain the RPE scale clearly to participants to ensure effective results.

Aquatic training improves balance and core stability. Balance and walking ability improved among older adults who trained in shallow water with resistance equipment for 90 minutes 3 times a week for 8 weeks (Katsura et al. 2009).

Water ameliorates running performance. In a study that compared electromyography (EMG) activity between dry–land and deep–water runners, researchers found similar but not identical muscle recruitment and concluded that, for healthy individuals, maximal velocity optimized neuromuscular responses in the legs (Alberton et al. 2015). Researchers noted that deep-water running (DWR) reduced ground-force impact by up to 85%.

Another study found that NCAA Division III cross-country athletes who wore aquatic training shoes during DWR achieved intensities closer to land–based runners than those who ran in the water barefoot. To complement land-based training, researchers also recommend wearing an aquatic training shoe to “heighten the perceptual and kinesthetic sense of running on land” (Killgore et al. 2010).

Water properties lead to less muscle soreness and damage. A study comparing high–intensity land- and water-based plyometrics programs found that training in water produced less inflammation and muscle soreness (Robinson et al. 2004).

A study designed to identify the mechanisms underlying this result compared the effects of resistance exercise in water and on land in young male subjects and found significantly less increase in creatine kinase—an indirect marker of muscle damage—from the water workout. Researchers concluded that water–based exercise is an appropriate choice for those who want to limit muscle damage (Pantoja et al. 2009).

Aquatic exercise lowers blood pressure. Postmenopausal women with hypertension who participated in a water aerobics training group for 12 weeks significantly reduced systolic blood pressure in an amount equal to women who participated in a comparable land-based training group. Control group members saw no drop in blood pressure (Arca et al. 2014).

Water fitness lowers blood sugar levels for people with type 2 diabetes. A recent study of 35 people with type 2 diabetes compared land-based training with aquatic exercise. All participants trained for 45 minutes 3 times a week for 12 weeks. Participants in both groups experienced a significant reduction in A1C levels—a measure of glucose control (Delevatti et al. 2016).

Exercise in the pool improves knee and hip osteoarthritis (OA). A Cochrane review of six randomized controlled studies found moderate-quality evidence that aquatic exercise may have small, short-term but clinically relevant effects on pain, disability and quality of life in people with knee and hip OA (Bartels et al. 2016).

More Participants and Changing Demographics

Program directors report that most water fitness classes still serve active older adults. At the same time, programs for young and middle-aged adults, special populations, and recreational and elite athletes are increasing. This reflects the expanded interest in water exercise. Julie See, director of education for the Aquatic Exercise Association in Nokomis, Florida, says, “AEA has seen a 20% increase in membership since 2012 and a 30% increase in education, live and online educational programs since 2012.”

Experts agree that, like land-based programming, water fitness is not “one size fits all,” and niche programs are stimulating transformation by appealing to specific interests and demographic groups. Social media campaigns are also raising awareness among younger generations.

Younger and Middle-Aged Adults

Historically a group fitness schedule may have offered water aerobics and a “Twinges in the Hinges” class, but today’s water fitness program exhibits the same variety you find in land–based programming. Ann Gilbert, master trainer for WATERinMOTION®, in Tampa Bay, Florida, says, “The aquatic student today is younger than in the past . . . and thrives on the variety of class formats offered. [He or she wants] to train in all aspects of fitness—including cardio, dynamic strength, boot camps, martial arts and the mind-body connection.”

Recreational and Elite Athletes

Athletes typically enter the pool only when they need rehabilitation from an injury. However, while in–pool rehab and prehab therapeutic trainings continue to grow, more collegiate and professional athletic coaches are seeing value in cross–training in water as a regular off- and on-season method. In addition, as events like triathlons, marathons, biathlons and Tough Mudder® competitions expand in popularity, more recreational athletes are looking to the pool to cross-train. See the sidebar “Why Healthy Athletes Need Water Training” for more.

Manuel Velasquez, movement lead instructor and department coordinator at Rancho La Puerta Resort & Spa, Tecate, Mexico, says, “Coaches that post pictures and stat results [on Facebook and Instagram] about combining water training with other HIIT land-based programs to increase agility, performance and strength are raising awareness among young fitness enthusiasts and athletes.” The “Resources” sidebar includes links to equipment options that target more athletic enthusiasts.

Special Populations

Research continues to substantiate the benefits of aquatic training for people with chronic conditions, and more people are coping with these issues. Consequently, allied medical organizations and healthcare professionals are recommending water exercise as a disease management tool.

“The AEA is now managing the Arthritis Foundation Aquatic Program to train program leaders to offer this structured program within the community and assist those living with arthritis and related conditions to include exercise as part of a healthy lifestyle,” says See.

Other special populations for whom water exercise is popular include people with type 2 diabetes, people with fibromyalgia, and those coping with disabilities that impair walking or balance—and therefore make land-based activities more challenging. “Our disabled participants improved their cardiovascular fitness and ADL to the point where their new mobility skills allowed them to live more independently,” says Sanders. “Time in water using the WaterFit® program led to significant quality–of–life changes that have persisted.”

Pool-based training is ideal for those who want to avoid excessive impact, overheating or elevated heart rates. These participants include people who’ve had joint replacements, those dealing with heart disease, prenatal and postpartum mothers, and aging athletes who are coping with a lifetime of wear and tear on joints.

Program Trends and New Training Options

Across the fitness industry, the focus is on higher-intensity trainings and recovery. Technological improvements are also expanding training options and equipment. Here’s a sampling of these influences on water fitness trends.

Aquatic bootcamp, HIIT and boxing. Experts note an increase in both deep– and shallow-water high-intensity interval training classes, as well as boxing and kickboxing formats. Irene Lewis–McCormick, MS, SCW certification faculty, of Des Moines, Iowa, says, “Aqua boot–camp circuit is my favorite time–based station workout.” She also teaches deep-water Tabata™. Carrie Haines, a personal trainer in Truckee, California, teaches aqua Tabata, an offering that draws a younger crowd, while deep-waterfitness attracts more men and athletes. See the sidebar “Adapt HIIT to the Water” for more.

Dance and barre. Land-based trends like yoga and Pilates continue to cross over and proliferate in the pool. Aqua Zumba® and barre-based classes are spreading, too. “I took barre to the water,” says Haines, a master trainer for Barre Above™. “Initially, it drew an older crowd, but now, since barre is so hot, it’s becoming more popular in general.”

Surf and turf. Sanders notes that more programs are blending water and land. “Mixing activities to avoid injury and burnout is good for long-term adherence,” she says. “People can increase the volume of exercise without increasing injury risk, and they can perform cardio-resistive exercises in one time-efficient HIIT session. Our studies showed that even when only one water session was added to a regular exercise program, ADL improved significantly. More sessions were better, but even one made a difference.”

Gilbert coached a local marathon walking team that included 18 weeks of on-road training and 4-week offseason pool trainings that consisted of water walking and aquatic strength training. Velasquez offered a “Mindful Triathlon” combining 30 minutes of hiking, 30 minutes of indoor cycling and 30 minutes of water fitness, to expose participants to activities they might not otherwise have tried.

Personal training. Both Baldwin and Edwards see an increase in demand for personal training and combine land- and water-based protocols to help clients succeed. “What’s missing is an explanation of ‘why’ people need to do the exercises,” says Baldwin. “If you can show clients that they can get the results they want with less strain and impact [in the water], they will do it.”

Edwards gives water exercise more credibility by emphasizing her own athletic experience—this helps clients accept what water workout can do. “Otherwise, I do not see the person again, as the first workout is usually not as intense [as it would be on land, because people first need to] learn how to do the moves.”

Equipment options. Training tools such as waterproof kettlebells and medicine balls, underwater treadmills, hot and cold plunge pools, and small pools with movable floors that allow for different training depths and have jets to create currents for overload are prompting more coaches to cross–train athletes in water.

In a HydroWorx® white paper, Alberto Salazar, head coach of the Nike Oregon Project, writes, “We don’t consider [using an underwater treadmill] an alternative to running outside. We consider it as important as running outside. It helps us become stronger by running against the resistance of the water, and it helps us recover from our dry land training.”

“Trending equipment-focused classes include trampolines, vertical poles for supporting the body in dance as well as strength moves, in-water boxing bags, underwater bikes and indoor standup paddleboards,” says See.

The Future of Water Fitness

Experts agree that water fitness is positioned for significant growth owing to changing demographics, improved equipment options and greater public awareness. “With renewed interest in HIIT, CrossFit® and other types of intense workouts, the time is ripe for program directors and fitness pros to give deep-water interval training another look,” Edwards observes.

Velasquez adds: “When attention is given to programming, scheduling and instructor education, [water fitness] turns around retention, referrals and overall customer satisfaction.” Since pool training offers a friendly, fun environment that promotes relationships, Lewis-McCormick thinks more fitness pros should tap into the strength of the “fitness tribe” that naturally emerges in pool classes. Instructors should bring successful classes to the attention of directors and managers.

At the same time, experts agree that education is key. “To bridge into medical fitness and broaden programs to include athletes and special pops, instructor education should be designed with respect to evidence–supported protocols,” says Sanders. As usual, personal trainers should conduct pre-; and posttraining assessments to encourage participants and validate progress. More allied healthcare professionals and athletic trainers will refer clients for aquatic training, and fitness pros need to be ready. A new era of water fitness is here.