High Versus Low Load Resistance Training

BACKGROUND: Previously we showed that 12 weeks of mixed-low resistance training (LOW+) significantly increased circulating BDNF in older male individuals.

OBJECTIVES: To examine the impact of 24 weeks detraining on circulating BDNF.

DESIGN: Randomized intervention study.

SETTING: Community-dwelling older adults.

PARTICIPANTS AND METHODS: Forty-seven out of 56 participants stopped training (detraining) after 12 weeks of resistance exercise (3x/week) at either HIGH-resistance (5 Males, 5 Females, 2x10-15 repetitions at 80%1RM), LOW-resistance (6 Males, 7 Females, 1x80-100 repetitions at 20%1RM), or mixed-low LOW+-resistance (6 Males, 8 Females, 1x60 repetitions at 20%1RM followed by 1x10-20 repetitions at 40%1RM), of whom 37 (aged 68±5 years) provided sufficient serum samples for BDNF analysis at baseline, 12 week and at 36 weeks (24 weeks detraining).

RESULTS: BDNF had initially increased by 31% (from 33.4±10.9 ng/mL to 44.5±13.2 ng/mL, p=0.005) after 12 weeks in the LOW+ exercise group in males and decreased by 26% (from 44.5±13.2 ng/mL to 32.9±10.7 ng/mL) after detraining, though not statistically significant (p=0.082). In females, no significant change in BDNF was found in any of the intervention groups (p>0.05), neither after training, nor detraining. At 36 weeks all of the subgroups showed BDNF levels comparable (all p>0.10) to baseline (before the exercise intervention).

CONCLUSIONS: Our results show that a 12-weeks LOW+ resistance exercise increases circulating BDNF in older male subjects but that this reduces back to baseline levels after 24 weeks of detraining. Continuous exercise adherence seems to be needed to sustain the training-induced effects on BDNF in older persons. Additional studies are needed to unravel the underlying mechanisms, as well as to confirm the observed sex difference.