UGA Concussion Research Laboratory, University of Georgia, Athens, GA,USA.
Department of Kinesiology, University of Georgia, Athens, GA,USA.
J Sport Rehabil. 2022 Jul 22;32(1):31-39. doi: 10.1123/jsr.2022-0075. Print 2023 Jan 1.
Neuromuscular function is altered acutely following concussion and theoretically linked to the subsequent postconcussion musculoskeletal injury risk. Existing research has only examined voluntary muscle activation, limiting mechanistic understanding. Therefore, our study aimed to examine voluntary and involuntary muscle activation between college-aged, concussed individuals when symptom-free and healthy matched controls.
Prospective, cross-sectional cohort laboratory study.
Concussed and healthy participants (n = 24; 58% male, age: 19.3 [1.1] y, mass: 70.3 [16.4] kg, height: 177.3 [12.7] cm) completed the superimposed burst (SB) neuromuscular assessment on their dominant limb within 72 hours after self-reporting asymptomatic (22.4 [20.2] d postinjury). Unnormalized and bodyweight-normalized quadriceps maximal voluntary isometric contraction torque (in newton meters), unnormalized and bodyweight-normalized electrically stimulated SB torque, pain (numeric 1-10) during SB, and the central activation ratio (in percentage) were assessed via the SB. Parametric and nonparametric analyses, 95% confidence intervals (95% CIs), and Hedges g (parametric) and Spearman ρ (nonparametric) effect sizes were used to examine group differences (α = .05).
The maximal voluntary isometric contraction torque (concussed: 635.60 N·m [300.93] vs control: 556.27 N·m [182.46]; 95% CI, -131.36 to 290.02; P = .443; d = 0.33), SB torque (concussed: 203.22 N·m [97.17], control: 262.85 N·m [159.07]; 95% CI, -171.22 to 51.97; P = .280; d = -0.47), and central activation ratio (concussed: 72.16% [17.16], control: 70.09% [12.63]; 95% CI, -10.68 to 14.83; P = .740; d = 0.14) did not differ between the concussed and control groups regardless of bodyweight normalization (P ≥ .344). Pain during the SB was significantly higher with a medium effect for participants with a concussion versus healthy controls (concussed: median = 7, control: median = 5; P = .046; ρ = -0.42).
These findings suggest concussed participants do not have statistically altered voluntary or involuntary quadricep neuromuscular function once asymptomatic compared with controls. Therefore, the elevated postconcussion musculoskeletal injury risk may not be attributed to lower-extremity muscle activation. Concussed participants displayed greater pain perception during the SB, which suggests somatosensory or perception changes requiring further examination.
在脑震荡后，神经肌肉功能会发生急性变化，理论上与随后的脑震荡后肌肉骨骼损伤风险有关。现有的研究仅检查了自愿肌肉激活，限制了对机制的理解。因此，我们的研究旨在检查无症状和健康匹配对照的大学生脑震荡个体的自愿和非自愿肌肉激活。
前瞻性、横断面队列实验室研究。
脑震荡和健康参与者（n=24；58%为男性，年龄：19.3[1.1]岁，体重：70.3[16.4]kg，身高：177.3[12.7]cm）在自我报告无症状后 72 小时内（损伤后 22.4[20.2]天）对优势肢体进行叠加爆发（SB）神经肌肉评估。通过 SB 评估未归一化和体重归一化的股四头肌最大等长收缩扭矩（牛顿米）、未归一化和体重归一化的电刺激 SB 扭矩、SB 期间的疼痛（数字 1-10）和中枢激活比（百分比）。使用参数和非参数分析、95%置信区间（95%CI）、Hedges g（参数）和 Spearman ρ（非参数）效应大小来检查组间差异（α=0.05）。
最大等长收缩扭矩（脑震荡：635.60N·m[300.93]，对照：556.27N·m[182.46]；95%CI，-131.36 至 290.02；P=0.443；d=0.33）、SB 扭矩（脑震荡：203.22N·m[97.17]，对照：262.85N·m[159.07]；95%CI，-171.22 至 51.97；P=0.280；d=-0.47）和中枢激活比（脑震荡：72.16%[17.16]，对照：70.09%[12.63]；95%CI，-10.68 至 14.83；P=0.740；d=0.14）在脑震荡组和对照组之间无论体重归一化如何均无统计学差异（P≥0.344）。与健康对照组相比，脑震荡参与者在 SB 期间的疼痛明显更高，具有中等效应（脑震荡：中位数=7，对照：中位数=5；P=0.046；ρ=-0.42）。
这些发现表明，与对照组相比，脑震荡参与者一旦无症状，其自愿或非自愿股四头肌神经肌肉功能就没有统计学上的改变。因此，脑震荡后肌肉骨骼损伤风险的增加可能不是由于下肢肌肉激活。脑震荡参与者在 SB 期间表现出更大的疼痛感知，这表明需要进一步检查躯体感觉或感知变化。
