Physiological Effects of Strength Training Incorporating Blood Flow Restriction Underwater / 日本温泉気候物理医学会雑誌

ABSTRACT

  Strength training performed while restricting blood flow is believed to cause the secretion of growth hormones under low load intensities and allow for muscle hypertrophy and increased muscle strength. This has potential clinical applications for elderly individuals and people with existing conditions. However, previous research has been performed on land, with hemodynamics and growth hormone secretion trends for training performed underwater unclear. Against this background, we investigated the effects of blood flow restriction training underwater on hemodynamics and plasma growth hormone (GH) levels. Twelve healthy university students were divided into two groups a localized immersion group where only the upper limb of the dominant hand was submerged, and a whole-body immersion group where participants were submerged to the xiphoid process. Immersed according to respective group protocols, both groups performed flexion and extension of the shoulder joint for 10 minutes with a pressurized cuff at the base of the upper arm under both 0 mmHg and 50 mmHg cuff pressures. Measured hemodynamics were heart rate, systolic blood pressure, and diastolic blood pressure. Plasma GH levels were measured from blood samples. This study revealed that underwater blood flow restriction strength training induced plasma GH level secretion under 50 mmHg conditions. In addition, high levels of GH secretion were shown in the localized immersion group for strength training even when the cuff was not pressurized. Conversely, no significant differences were evident in any measured hemodynamic categories. Results suggest that, in addition to cuff pressure, blood flow restriction training is affected by the body part immersed in water.