Background & Aims
Exercise-induced hypoalgesia (EIH) is a phenomenon in which pain sensitivity is temporarily reduced after exercise. However, recent studies have reported that EIH effect may be reduced in the elderly patients. Reduction of skeletal muscle mass (i.e., sarcopenia) and dysfunction of endogenous pain modulation system are risk factors associated with severe pain symptoms in the elderly patients and may act as barriers inhibiting the EIH effect. If the EIH effect and its barriers in the elderly become clear, it may lead to the establishment of effective pain treatment for elderly patients. This study aimed to investigate the EIH effect and its associated factors in elderly patients with proximal femoral fractures after surgery.
Methods
We included 60 elderly patients with proximal femoral fractures after surgery. Participants will be randomly assigned to the exercise group or the control group. All participants, in addition to daily standardized physical therapy, performed low-intensity aerobic exercise in the exercise group, and passive stretching in the control group for 15 minutes. We assessed the baseline on demographic characteristics (age, gender, mini-mental state examination [MMSE], skeletal muscle mass index [SMI], and conditioned pain modulation [CPM]). EIH was assessed using a numerical rating scale (NRS, 0 to 10), pressure pain threshold (PPT) in the bilateral hip, affected side lower leg and forearm. NRS was defined as pain during walking. The analysis compared the changes in NRS and PPT in both groups. In addition, PPT change (?PPT) of the affected hip was calculated as an index of EIH effect, and the correlation with demographic characteristics was investigated in the exercise group.
Results
There was no significant difference between groups in demographic characteristics (age: exercise group = 80.5 ± 7.8 years, control group = 79.6 ± 7.4 years; SMI: exercise group = 5.6 ± 1.1 kg/m2, control group = 5.2 ± 0.7 kg/m2; CPM: exercise group = 7.9 ± 15.7 %, control group = 8.6 ± 13.9 %). There were no significant differences in NRS (exercise group: pre = 2.4 ± 2.5?post= 2.3 ± 2.5; control group: pre = 1.8 ± 2.1, post = 1.7 ± 2.1) between both groups by intervention. PPT significantly increased in all locations in the exercise group (affected hip: pre = 30.8 ± 10.1 N, post = 33.2 ± 11.2 N, P < 0.01) after the intervention, while in the control group (affected hip: pre = 27.8 ± 7.6 N, post = 29.8 ± 7.7 N, P < 0.05), a significantly increased only in the affected hip. However, ?PPT in both groups did not indicate a clinically important difference. The ?PPT in the exercise group showed a significant positive correlation with SMI (r = 0.31, P < 0.05) and CPM (r = 0.44, P < 0.05).
Conclusions
This study showed no clinically meaningful difference in EIH of elderly patients due to active or passive exercise. Moreover, those with low EIH effects exhibited a decrease in skeletal muscle mass and CPM. Therefore, it has been suggested that the EIH effect was poor in the elderly, and that sarcopenia and dysfunction of endogenous pain modulation system are barrier factors for EIH. In the future, when applying exercise therapy to the pain treatment and management of elderly patients with postoperative pain, it will be necessary to also consider barrier factors.
References
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Presenting Author
Shuhei Yamaguchi
Poster Authors
Topics
- Pain in Special Populations: Elderly