Soft tissue manipulation enhances recovery of muscle mass in a disuse model of sarcopenia

Abstract

Context: Sarcopenia is a disease characterized by low muscle mass and function that places individuals at greater risk of disability, loss of independence, and death. Current therapies include addressing underlying performance issues, resistance training, and/or nutritional strategies. However, these approaches have significant limitations, and chronic inflammation associated with sarcopenia may blunt the anabolic response to exercise and nutrition. This presents an unmet need for treatment strategies that promote gains in muscle function. One such possibility is soft tissue manipulation (STM), which is a noninvasive, nonpharmacological mechanotherapy employed by osteopathic physicians, physiotherapists, and massage therapists, wherein soft tissues are subjected to mechanical forces delivered by hand or by an instrument. However, the molecular effects of STM in sarcopenia remain largely unknown.

Objectives: In the present study, we utilized a rat model of sarcopenia due to disuse atrophy and examined the effects of STM on recovery of muscle mass and regulation of pro-/anti-inflammatory cytokines.

Methods: Ten-week-old male Brown Norway rats were subjected to 2-week hindlimb suspension (HLS) and then allowed to re-ambulate for 8 days with or without instrument-assisted soft tissue manipulation (IASTM) applied to the right hindlimb. Muscle weights were determined for treated and nontreated hindlimbs, and membrane-based cytokine arrays were performed on treated tissue and serum.

Results: Following suspension, IASTM enhanced the effectiveness of re-ambulation (Re-A) on muscle mass recovery in both treated and contralateral limbs. This was associated with changes in numerous cytokines in treated skeletal muscle and sera. Several factors we observe to be regulated were also shown to be regulated by STM in other studies, including ciliary neurotrophic factor (CNTF), IL-1β, IL-2, IL-3, IL-13, ICAM-1, and tumor necrosis factor alpha (TNF-α), whereas others are reported for the first time.

Conclusions: Our study adds further support for the role of manual therapy in musculoskeletal health and details molecular-level effects in both target tissue and circulation. STM may hold promise for recovering muscle mass and function related in conditions of atrophy such as age-related sarcopenia.

Keywords: inflammation; manual therapy; muscle atrophy; rehabilitation; sarcopenia; soft tissue.

Figure 1:

HLS results in skeletal muscle atrophy and changes in cytokine levels. (A) Images of HLS setup, wherein cages were modified with a bar and rolling pully (left) to which animal tails were affixed utilizing foam tape (right). (B) Mass of gastrocnemius immediately after sacrifice from weight-bearing controls (control) and animals subjected to 2-week HLS. Circles represent gastrocnemius mass from individual animals expressed as percent relative to the mean weight for the control group. Bar is mean ± standard error of the mean (SEM). n=5 for control and n=7 for HLS. Data were determined to be normally distributed by the Shapiro-Wilk test. * indicates p<0.05 by unpaired t-test. Raw weights obtained immediately after sacrifice and after 12 days of drying may be found in Supplemental Figures 1A and B. (C, D) membrane arrays utilizing quadricep homogenates obtained from control or HLS animals. Homogenates were pooled at equal ratios within groups for n=5 for control and n=6 for HLS. Red boxes in C indicate factors detailed in D, which are those altered by≥25 % in HLS compared to control. In D, data are expressed as fold change relative to control. Complete quantification may be found in Supplemental Table 1.

Figure 2:

Membrane arrays utilizing sera obtained from control or HLS animals. Sera were pooled at equal ratios within groups for n=5 for control and n=7 for HLS. Red boxes in (A) indicate factors detailed in (B), which are those altered by≥25 % in HLS compared to control. (B) Data are expressed as fold change relative to control. Complete quantification may be found in Supplemental Table 2.

Figure 3:

STM enhances muscle mass recovery following disuse atrophy. (A) Schematic of timeline for animals subjected to HLS then 8 days of Re-A or Re-A+IASTM. IASTM was carried out every other day beginning the day following release from HLS for a total of four sessions (Tx). All animals were euthanized 8 days following HLS. (B) Images of the IASTM technique. (C) Mass of ipsilateral gastrocnemius immediately after sacrifice from Re-A and Re-A+IASTM animals. Circles represent gastrocnemius mass from individual animals expressed as percent relative to the mean lost in the HLS group. Bar is mean ± standard error of the mean (SEM). n=7 for Re-A and n=8 for Re-A+IASTM. Data were determined to be normally distributed by the Shapiro-Wilk test. * indicates p<0.05 by unpaired t-test. Raw weights obtained immediately after sacrifice and after 12 days of drying may be found in Supplemental Figures 1A and B.

Figure 4:

Membrane arrays utilizing quadricep homogenates obtained from animals subjected to HLS then 8 days of Re-A or Re-A+IASTM. Homogenates were pooled at equal ratios within groups for n=7 for Re-A and n=8 for Re-A+IASTM. Red boxes in (A) indicate factors detailed in B, which are those altered by≥25 % in HLS compared to control. (B) Data are expressed as fold change relative to control. Complete quantification may be found in Supplemental Table 3.

Figure 5:

Membrane arrays utilizing sera homogenates obtained from animals subjected to HLS then 8 days of Re-A or Re-A+IASTM. Homogenates were pooled at equal ratios within groups for n=7 for Re-A and n=8 for Re-A+IASTM. Red boxes in (A) indicate factors detailed in (B), which are those altered by≥25 % in HLS compared to control. (B) Data are expressed as fold change relative to control. Complete quantification may be found in Supplemental Table 4.

Figure 6:

Mass of contralateral gastrocnemius immediately after sacrifice from Re-A and Re-A+IASTM animals. Circles represent gastrocnemius mass from individual animals expressed as percent relative to the mean lost in the HLS group. Bar is mean ± standard error of the mean (SEM). n=7 for Re-A and n=8 for Re-A+IASTM. Data were determined to be normally distributed by the Shapiro-Wilk test. * indicates p<0.05 by unpaired t-test. Raw weights obtained immediately after sacrifice and after 12 days of drying may be found in Supplemental Figures 1C and D.