Strength gains after 12 weeks of resistance training correlate with neurochemical markers of brain health in older adults: a randomized control 1H-MRS study

Abstract

Physical exercise is considered a potent countermeasure against various age-associated physiological deterioration processes. We therefore assessed the effect of 12 weeks of resistance training on brain metabolism in older adults (age range: 60-80 years). Participants either underwent two times weekly resistance training program which consisted of four lower body exercises performed for 3 sets of 6-10 repetitions at 70-85% of 1 repetition maximum (n = 20) or served as the passive control group (n = 21). The study used proton magnetic resonance spectroscopy to quantify the ratio of total N-acetyl aspartate, total choline, glutamate-glutamine complex, and myo-inositol relative to total creatine (tNAA/tCr, tCho/tCr, Glx/tCr, and mIns/tCr respectively) in the hippocampus (HPC), sensorimotor (SM1), and prefrontal (dlPFC) cortices. The peak torque (PT at 60°/s) of knee extension and flexion was assessed using an isokinetic dynamometer. We used repeated measures time × group ANOVA to assess time and group differences and correlation coefficient analyses to examine the pre-to-post change (∆) associations between PT and neurometabolite variables. The control group showed significant declines in tNAA/tCr and Glx/tCr of SM1, and tNAA/tCr of dlPFC after 12 weeks, which were not seen in the experimental group. A significant positive correlation was found between ∆PT knee extension and ∆SM1 Glx/tCr, ∆dlPFC Glx/tCr and between ∆PT knee flexion and ∆dlPFC mIns/tCr in the experimental group. Overall, findings suggest that resistance training seems to elicit alterations in various neurometabolites that correspond to exercise-induced "preservation" of brain health, while simultaneously having its beneficial effect on augmenting muscle functional characteristics in older adults.

Keywords: Aging; Brain metabolism; Glutamate; N-acetylaspartate; Neurogenesis; Sarcopenia; Strength training.

Conflict of interest statement

The authors declare no competing interests.

© 2023. The Author(s).

Figures

Fig. 1

Example of voxel placement along with processed MR spectra in a the left hippocampus (HPC), b the left primary sensorimotor cortex (SM1), and c the right dorsolateral prefrontal cortex (dlPFC) in one participant

Fig. 2

The paired mean difference for PT in EXP and CONT group are shown in the above Cumming estimation plot. The raw data is plotted on the upper axes; each paired set of observations for each participant from PRE to POST is connected by a line. Blue lines indicate POST minus PRE > 0 whereas orange lines indicate POST minus PRE 

Fig. 3

The mean differences between responders and non-responders at baseline is shown in the above Gardner-Altman estimation plots for a MoCA score (n = responders, 8; non-responders, 12) and (b) SM1 tNAA/tCr (n = responders, 7; non-responders, 12). Individual results for both groups are plotted on the left axes; the mean difference is plotted on a floating axes on the right as a bootstrap sampling distribution. The mean difference is depicted as a dot between the Gaussian curve and the 95% confidence interval is indicated by the ends of the vertical error bar. Abbreviations: MoCA, Montreal cognitive assessment; NR-R, mean difference between non-responders and responders; SM1 tNAA/tCr, sensorimotor cortex concentration ratio of total N-acetyl aspartate relative to total creatine

Fig. 4

The linear relationship that survived FDR procedure between changes in strength and neurometabolite ratios were a ∆PT knee extension and ∆SM1 tNAA/tCr (n = EXP, 16; CONT, 16), b ∆PT knee extension and ∆dlPFC Glx/tCr (n = EXP, 17; CONT, 13), and c ∆PT knee flexion and ∆dlPFC mIns/tCr (n = EXP, 19; CONT, 14), in EXP (blue) and CONT (orange) group participants. See Supplementary Fig. 2 for all relationships. Abbreviations: SM1, sensorimotor cortex; Glx, glutamine-glutamate complex; tCr, total creatine; PT, peak torque; dlPFC, pre-frontal cortex; mIns, myo-inositol; EXP, experimental group; CONT, control group