Daily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilization.
Level 2 - randomized trial
Controlled experimental human trial with sham comparator
PubMed 31046520 · doi:10.1152/japplphysiol.01098.2018
What was done
Twenty-three healthy volunteers (11 women, 12 men) underwent 10 days of lower-limb immobilization. Participants were assigned to either a daily sham treatment (Imm) or a targeted daily 2-hour heat treatment applied via pulsed shortwave diathermy (Imm + H). Before and after the 10-day disuse period, researchers measured intramuscular temperature, heat shock protein (HSP) expression, mitochondrial respiration, mitochondrial complex proteins via vastus lateralis muscle biopsies, and muscle cross-sectional area (CSA) using MRI.
What was found
Pulsed shortwave diathermy increased intramuscular temperature by 4.2 ± 0.29°C (P < 0.0001), while sham treatment showed no change. In the Imm + H group, HSP70 and HSP90 increased by 25 ± 6.6% and 20 ± 7.4% (P < 0.05), respectively, with no change in the Imm group. Heat therapy significantly attenuated the disuse-induced reduction in coupled myofiber respiratory capacity (-8 ± 6.0% with heat vs. -27 ± 5.2% with sham, P = 0.0041) and uncoupled respiration (-10 ± 3.9% vs. -25 ± 7.0%, P = 0.0302), and preserved proteins across all five mitochondrial complexes (P < 0.05). Muscle atrophy was reduced in the heat group compared to sham at both the whole-muscle CSA level (-4.5 ± 1.09% vs. -7.6 ± 0.96%, P = 0.0374) and the myofiber CSA level (-5.8 ± 1.49% vs. -10.8 ± 1.52%, P = 0.0322).
Why it matters
Targeted local heat therapy via diathermy represents a non-invasive, passive countermeasure that mitigates disuse-induced muscle wasting and preserves mitochondrial respiratory capacity during periods of forced limb immobilization.
Limits
The study was conducted in a small cohort (n = 23) of young, healthy volunteers, limiting direct generalizability to clinical populations such as post-surgical, injured, or elderly individuals. The immobilization period was brief (10 days). Functional mechanical outcomes (such as maximal voluntary contraction strength or power output) and post-remobilization recovery trajectories were not reported in the abstract.
Cited by
- supports Applying local heat to an immobilized leg prevents muscle atrophy by approximately 40%.