Introduction: Aging is linked with increased physical inactivity, which is associated with many unfavorable health consequences including decreased cardiorespiratory fitness levels. This is disconcerting as low cardiorespiratory fitness is strongly related to increased risk of cardiovascular disease (CVD), mortality from CVD, and all-cause mortality (Blair et al., 1996). In fact, it has recently been suggested that cardiorespiratory fitness is the ultimate marker for risk stratification and health outcomes (Franklin, 2007). Increased physical inactivity in older adults may be partially attributable to orthopedic challenges and balance impairments, which makes familiar and popular land-based exercises such as walking, jogging, and cycling more difficult. In part, for these reasons aquatic exercise and water aerobics have become an increasingly popular, alternative form of aerobic exercise (Benelli et al., 2004). Although there is a considerable body of literature concerning the various health benefits associated with aquatic exercise, research focused on the specific physiological and metabolic responses to water aerobics is relatively sparse and has mostly been completed with younger participants (Eckerson & Anderson, 1992; Darby & Yaekle, 2000; Campbell et al., 2003).
Purpose: The purpose of this study was (a) to assess the cardiovascular and metabolic responses to water aerobic exercise and (b) to determine if water aerobics exercise meets the American College of Sports Medicine (ACSM) guidelines for improving and maintaining cardiorespiratory fitness.
Methods: Fourteen, apparently healthy, men and women (M ± SD age, height, weight, % body fat, and maximal oxygen uptake (VO2max): 57.4 ± 7.6 yr, 171.3 ± 7.8 cm, 89.9 ± 13.9 kg, 31.9 ± 5.9%, and 31.0 ± 8.3 mL/kg/min, respectively) completed a maximal treadmill exercise test and 50-min water aerobics session. Cardiovascular and metabolic data were collected via a CosMed K4b2 portable calorimetric measurement system (Rome, Italy).
Results: Mean exercise intensity was 43.4% and 42.2% of heart rate reserve (HRR) and maximal oxygen uptake reserve (VO2R), respectively. Training intensity in metabolic equivalents (METs) was 4.26 ± 0.96. Total net energy expenditure for the exercise session was 249.1 ± 94.5 kcal.
Conclusion: Our findings indicate that water aerobics is a feasible alternative to land-based exercise for older adults that fulfills the ACSM guidelines for improving and maintaining cardiorespiratory fitness. This is critical, as low cardiorespiratory fitness may contribute to premature mortality in middle-aged and older adults (Fitzgerald et al., 1997). Moreover, decreased cardiorespiratory fitness contributes to a reduction in physiological functional capacity and eventually can result in loss of independence (Dempsey & Seals, 1995; Hagberg et al., 1994). Overall, these findings are important for fitness instructors, physical therapists, and others who design exercise programs for older adults.