The effect of the whole-body isometric resistance training program on muscle strengths, brain derived neurotrophic factor, and quality of life in the community-dwelling middle-aged and older adults.

Background: The isometric form has been recommended as an effective alternative for resistance training in the middle-aged and older adults; however, the effect of the whole-body isometric resistance training (WB-IRT) remained unknown. The aim of the present study was to examine the effect of the WB-IRT on muscle strengths, brain derived neurotrophic factor (BDNF), and quality of life (QoL) in the community-dwelling middle-aged and older adults.

Methods: Thirty-five community-dwelling middle-aged and older adults were randomly assigned to 12 weeks of WB-IRT (28 participants, 62.18±8.87) or control group (seven participants, 59.86±6.31). Isokinetic muscle strength was assessed by Biodex isokinetic testing. Blood samples were collected for plasma BDNF assays. WHOQOL-BREF questionnaire was used to assess their QoL. All measurements were collected at baseline and at least one month after this WB-IRT program.

Results: There was significant interaction of group and time in plasma BDNF concentrations (F(1, 29)=5.533, P=0.026, ηp²=0.160) and QoL (F(1, 29)=7.313, P=0.011, η²=0.201). For the between-group differences, the maximum peak torque of the knee extension and flexion in WB-IRT group instead of control group were significantly higher in the post-training than in the pre-training (P<0.05). Plasma BDNF concentrations was significantly elevated from pre-training to post-training in WB-IRT group (P<0.001), rather than control group. QoL was significantly decreased from pre-training to post-training in control group (P=0.038). Furthermore, hierarchical regression analyses showed the change of plasma BDNF concentrations could significantly predict post-training QoL in the community-dwelling middle-aged and older adults (β=0.520, P=0.003).

Conclusions: Our results showed that the effect of this WB-IRT program was able to enhance muscle strengths, increase plasma BDNF concentrations, and improve QoL in the middle-aged and older adults. These are possibly alarming in the change of plasma BDNF concentrations, thereby associating QoL. This study recommends that the WB-IRT program is effective in enhancing both physical and psychosocial wellbeing among middle-aged and older adults. Further research is warranted to compare various modalities of resistance training and to evaluate the sustainability of its effects on physical and psychosocial well-being.