The purpose of this study was to determine the impact of localized cooling of the skeletal muscle during rest on mitochondrial related gene expression. Thermal wraps were applied to the vastus lateralis of each limb of 12 participants. One limb received a cold application (randomized) (COLD), while the other did not (RT). Wraps were removed at the 4 h time point and measurements of skin temperature, blood flow, and intramuscular temperature were taken prior to a muscle biopsy. RT-qPCR was used to measure expression of genes associated with mitochondrial development. Skin and muscle temperatures were lower in COLD than RT (p < 0.05). Femoral artery diameter was lower in COLD after 4 h (0.62 ± 0.05 cm, to 0.60 ± 0.05 cm, p = 0.018). Blood flow was not different in COLD compared to RT (259 ± 69 mL·min^–1 vs. 275 ± 54 mL·min^–1, p = 0.20). PGC-1α B and GABPA expression was higher in COLD relative to RT (1.57-fold, p = 0.037 and 1.34-fold, p = 0.006, respectively). There was no difference (p > 0.05) in the expression of PGC-1α, NT-PGC-1α, PGC-1α A, TFAM, ESRRα, NRF1, GABPA, VEGF, PINK1, PARK 2, or BNIP3-L. The impact of this small magnitude of difference in gene expression of PGC-1α B and GABPA without alterations in other genes are unknown. There appears to be only limited impact of local muscle cooling on the transcriptional response related to mitochondrial development.

McGlynn, ML, Rosales, AM, Collins, CW, and Slivka, DR. The influence of local cold application and resistance exercise on the mRNA response of skeletal muscle. J Strength Cond Res 39(11): e1272–e1278, 2025—Cold application post exercise is common practice despite empirical evidence suggesting it impairs muscle growth signaling. Our purpose was to determine the effects of local cold application and resistance exercise on muscle growth/breakdown gene expression. Twelve subjects completed a bilateral resistance exercise bout to volitional fatigue (leg press, leg extension) while wearing a thermal wrap on 1 limb (10° C fluid, EX + COLD) and no wrap contralaterally (EX). Bilateral vastus lateralis biopsies, skin temperature, and intramuscular temperature were collected pre intervention, post resistance exercise (temperatures only), and 4 hours post exercise. Statistical significance was set at p < 0.05. After 4 hours of cooling, skin ( p < 0.001) and intramuscular temperatures ( p < 0.001) were lower in the EX + COLD (20.4 ± 0.6, 26.1 ± 0.9° C) than in the EX limb (31.7 ± 0.6, 35.1 ± 0.3° C). Despite these temperature decreases, local cooling did not differentially influence myogenic and proteolytic gene expression ( p > 0.05). Resistance exercise was the primary influence on gene expression change. Favorable myogenic gene expression changes were exhibited by Myogenin (increase, p = 0.007), Myogenic Factor 6 (increase, p = 0.002), and Myostatin (decrease, p < 0.001). However, myogenic gene Myogenic Factor 5 decreased ( p < 0.001). All other myogenic genes went unchanged (Myogenic Differentiation 1 , p = 0.665; Myocyte Enhance Factor 2a , p = 0.074; Ribosomal Protein S3 , p = 0.773; Ribosomal Protein L3-Like , p = 0.118). Proteolytic gene expression changes were exhibited by Muscle Unique Ring Finger 1 (increase, p = 0.002) and Atrogin-1 (decrease, p = 0.020). However, F-box protein 32 went unchanged ( p = 0.980). Local cooling may be paired with a resistance exercise bout because of minimal influence after 4 hours of cooling on skeletal muscle growth/breakdown mRNA signaling.