title: Cardiorespiratory responses to underwater treadmill walking in healthy females.
abstract: This study compared the cardiorespiratory responses of eight healthy women (mean age 30.25 years) to submaximal exercise on land (LTm) and water treadmills (WTm) in chest-deep water (Aquaciser). In addition, the effects of two different water temperatures were examined (28 and 36 degrees C). Each exercise test consisted of three consecutive 5-min bouts at 3.5, 4.5 and 5.5 km x h(-1). Oxygen consumption (VO2) and heart rate (HR), measured using open-circuit spirometry and telemetry, respectively, increased linearly with increasing speed both in water and on land. At 3.5 km x h(-1) VO2 was similar across procedures [chi = 0.6 (0.05) l x min(-1)]. At 4.5 and 5.5 km x h(-1) VO2 was significantly higher in water than on land, but there was no temperature effect (WTm: 0.9 and 1.4, respectively; LTm: 0.8 and 0.9 l x min(-1), respectively). HR was significantly higher in WTm at 36 degrees C compared to WTm at 28 degrees C at all speeds, and compared to LTm at 4.5 and 5.5 km x h(-1) (P < or = 0.003). The HR-VO2 relationship showed that at a VO2 of 0.9 l x min(-1) x HR was higher in water at 36 degrees C (115 beats x min[-1]) than either on land (100 beats min[-1]) or in water at 28 degrees C (99 beats x min[-1]). The Borg scale of perceived exertion showed that walking in water at 4.5 and 5.5 km x h(-1) was significantly harder than on land (WTm: 11.4 and 14, respectively; LTm: 9.9 and 11, respectively; P < or = 0.001). These cardiorespiratory changes occurred despite a slower cadence in water (the mean difference at all speeds was 27 steps/min). Thus, walking in chest-deep water yields higher energy costs than walking at similar speeds on land. This data has implications for therapists working in hydrotherapy pools.
authors.affiliation: Physiotherapy Department, Royal United Hospital, Bath, UK.
authors.forename: J
authors.initials: J
authors.lastname: Hall
authors.forename: I A
authors.initials: IA
authors.lastname: Macdonald
authors.forename: P J
authors.initials: PJ
authors.lastname: Maddison
authors.forename: J P
authors.initials: JP
authors.lastname: O'Hare
mesh_terms: D000328:Adult; D001794:Blood Pressure; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D007101:Immersion; D010101:Oxygen Consumption; D011674:Pulse; D013696:Temperature; D014867:Water
chemical_list: D014867:Water