Aims: To compare the postactivation potentiation effects of isometric contraction until failure in double- and single-leg tasks on older women’s balance. Methods: The one-legged balance test was performed before and immediately after a rise-to-toes task until the task failure. Older women were divided into two groups: a group performed the task with double leg (n = 43) and the other group with single-leg support (n = 55). Results: The single-leg group showed slower velocity of sway post rise-to-toes task (pre = 4.02 ± 1; post = 3.78 ± 1.15 m/s; p = .04) without differences for the center of pressure path length (pre = 79 ± 21; post = 75 ± 23 cm; p = .08). In the double-leg group, faster velocity of sway (pre = 4 ± 1.22; post = 4.25 ± 1.13; p = .03) and increased center of pressure path length (pre = 80 ± 24; post = 85 ± 23 cm; p = .03) were observed after the task. Conclusions: The single-leg group showed improved balance outcomes due to postactivation potentiation, while the double-leg group showed worsened balance consistent with muscle fatigue.
Ilha G. Fernandes, Matheus A. Souza, Matheus L. Oliveira, Bianca Miarka, Michelle A. Barbosa, Andreia C. Queiroz and Alexandre C. Barbosa
Hélcio Kanegusuku, Andréia C.C. Queiroz, Valdo J.D. Silva, Marco T. de Mello, Carlos Ugrinowitsch and Cláudia L.M. Forjaz
The effects of high-intensity progressive resistance training (HIPRT) on cardiovascular function and autonomic neural regulation in older adults are unclear. To investigate this issue, 25 older adults were randomly divided into two groups: control (CON, N = 13, 63 ± 4 years; no training) and HIPRT (N = 12, 64 ± 4 years; 2 sessions/week, 7 exercises, 2−4 sets, 10−4 RM). Before and after four months, maximal strength, quadriceps cross-sectional area (QCSA), clinic and ambulatory blood pressures (BP), systemic hemodynamics, and cardiovascular autonomic modulation were measured. Maximal strength and QCSA increased in the HIPRT group and did not change in the CON group. Clinic and ambulatory BP, cardiac output, systemic vascular resistance, stroke volume, heart rate, and cardiac sympathovagal balance did not change in the HIPRT group or the CON group. In conclusion, HIPRT was effective at increasing muscle mass and strength without promoting changes in cardiovascular function or autonomic neural regulation.
Fernando S. Lobo, Andreia C.C. Queiroz, Natan D. Silva Junior, Fabio L. Medina, Luiz A.R. Costa, Tais Tinucci and Claudia L.M. Forjaz
Background: Drinking water is recommended before and after exercise to avoid dehydration. However, water ingestion may mitigate or prevent postexercise hypotension. This study investigated the effects of intentional hydration on postaerobic exercise hemodynamics and autonomic modulation. Methods: A total of 18 young men randomly underwent 4 experimental sessions as follows: (1) control with intentional hydration (1 L of water in the previous night, 500 mL 60 min before the intervention, and 1 mL for each 1 g of body mass lost immediately after the intervention); (2) control without intentional hydration (ad libitum water ingestion before the intervention); (3) exercise (cycle ergometer, 45 min, 50% of VO2peak) with intentional hydration; and (4) exercise without intentional hydration. Hemodynamic and autonomic parameters were measured before and after the interventions and were compared by 3-way analysis of variance. Results: Intentional hydration did not change any postexercise hemodynamic nor autonomic response. Exercise decreased systolic blood pressure and stroke volume (−4.1 [0.8] mm Hg and −4.9 [1.5] mL, P < .05), while increased cardiac sympathovagal balance (0.3 [0.3], P < .05) during the recovery. In addition, it abolished the increase in diastolic blood pressure and the decrease in heart rate observed in the control sessions. Conclusion: Intentional hydration does not modify the hypotensive effect promoted by previous aerobic exercise and did not alter its hemodynamic and autonomic mechanisms.