Effect of Low-Load Blood Flow Restricted Training on Volitional Activation of Knee Extensor Muscles in Subjects with Knee Joint Impairment
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 36
- 试验地点
- 4
- 主要终点
- Quadriceps muscle isometric strength
研究概览
简要总结
The aim of this study was to investigate whether 4 weeks of exercise training against low mechanical resistance in combination with partial blood flow restriction has an additional therapeutic effect on the patients' ability to activate the knee extensor muscle. Patients with chronic deficits in muscle strength due to knee injuries or surgery on one leg were invited to participate in this study on a completely voluntary basis.
详细描述
The effects of low-load exercise with blood flow restriction (BFR) on the ability to voluntarily activate skeletal muscle in people with joint injuries are poorly understood. The aim of our study was to investigate the effects of low-load BFR training on the level of voluntary activation (AL) of the quadriceps femoris muscle assessed using the interpolated twitch technique in people with different knee joint injuries. Thirty-three orthopedic patients assigned to either the BFR group or the SHAM-BFR group participated in the study. Over a period of four weeks, the participants completed 12 training sessions of unilateral knee extension and leg press at 30 RM. The BFR group trained with a pneumatic cuff-induced blood flow restriction (pressure = 120-140 mmHg), while the SHAM-BFR group trained with a sham blood flow restriction (pressure = 20 mmHg) that did not interfere with normal muscle perfusion. The assessment of knee muscle capacity and function consisted of dynamometric measurements of maximal isometric strength and endurance of the knee extensor muscles, level of voluntary muscle activation, surface electromiography, pain intensity and assessment of perceived exertion. All tests and measurements were performed twice, once before the intervention (baseline) and once at the end of the 4-week training period (POST).
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Double (Participant, Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 55 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •no systemic illness,
- •no history of injuries to the contralateral knee,
- •pain intensity during exercise ≤ 2 on numeric pain rating scale (0-10).
排除标准
- •neuromuscular impairments,
- •spine or other lower limb injuries,
- •presence or history of any vascular diseases or deep vein thrombosis
- •pain intensity during exercise ≥ 3 on numeric pain rating scale (0-10).
结局指标
主要结局
Quadriceps muscle isometric strength
时间窗: Baseline and 4 weeks (post intervention)
The measurement of the torque of the maximum volitional isometric contraction (MVIC) of the quadriceps femoris (QF) was performed on an isometric knee joint dynamometer. The test subject was seated, the hip joint was flexed to 85° and the lever arm was locked at 60° knee flexion. After warming up, the subject was instructed to perform the MVIC for 3-5 seconds with arms crossed over the chest, with no upper body movements allowed. Three consecutive MVICs were performed with each leg, separated by a 30-second rest period. The experimenter gave the subjects strong verbal encouragement during the tests. The highest average 1-second torque (Nm) of the three trials was considered relevant and used for further analysis.
Maximal voluntary activation level of quadriceps muscle
时间窗: Baseline and 4 weeks (post intervention)
The degree of QF maximal voluntary activation (VAmax) was calculated as the ratio between the highest interpolated twitch contraction torque achieved during MVIC and the highest muscle twitch torque at rest measured during the first 10-second recovery period of after MVIC. The value is expressed as a percentage (%).
Quadriceps muscle isometric endurance
时间窗: Baseline and 4 weeks (post intervention)
The test of QF isometric endurance was performed on an isometric knee joint dynamometer. The test subject was seated with the hip joint flexed to 85° and the lever arm locked at 60° knee flexion. After warming up, the test subject was instructed to attain 60% MVIC torque displayed on a computer screen and to maintain this until voluntary failure. The experimenter gave the subjects strong verbal encouragement during the test. QF muscle endurance was measured in seconds (s).
Voluntary activation level of quadriceps muscle during isometric endurance test
时间窗: Baseline and 4 weeks (post intervention)
The degree of QF voluntary activation was evaluated in 10-s intervals during the isometric endurance test (VAendur). It was calculated as the ratio between the twitch torque attained in a given time interval and the highest muscle twitch torque at rest measured during the 20-second recovery period after the test. The value was expressed as a percentage (%).
Surface EMG amplitude of quadriceps muscle during isometric endurance test
时间窗: Baseline and 4 weeks (post intervention)
The change in activation of v. medialis, v. lateralis and rectus f. muscles was measured using surface EMG during the isometric endurance test. The electrodes were positioned according to the SENIAM standards (Hermens et al., 2000) to avoid overlapping of the innervation zones and cross-talk between the muscles. EMG activity was amplified using a four-channel monitoring device with a sampling rate of 1000 Hz, an input impedance of 2MΏ and a bandwidth of 1-500 Hz. Smoothing the root mean square (RMS) of the filtered signal with a time window of 3000 ms was used to quantify the EMG amplitude (mV). The RMS EMG during the endurance test was expressed as percentage of the highest value attained during MVIC (% RMS EMG max).
次要结局
- knee and muscle pain(during each training session, 3-times per week, for 4 weeks)
- ratings of perceived exertion(during each training session, 3-times per week, for 4 weeks)
研究者
Alan Kacin
Head of Laboratory
University of Ljubljana