Effect of LL-BFRE Training on Volitional Muscle Activation in Subjects with Knee Joint Impairment
- Conditions
- Arthrogenic Muscle InhibitionKnee InjuriesKnee Surgery
- Interventions
- Other: low-load blood flow restriction (BFR) trainingOther: low-load resistance training
- Registration Number
- NCT06603532
- Lead Sponsor
- University of Ljubljana
- Brief Summary
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.
- Detailed Description
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).
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 36
- no systemic illness,
- no history of injuries to the contralateral knee,
- pain intensity during exercise ≤ 2 on numeric pain rating scale (0-10).
- 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).
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description low-load blood flow restriction (BFR) resistance training low-load blood flow restriction (BFR) training Group of patients that performed the experimental exercise training against low mechanical resistance (workload) with blood flow restriction (BFR) in the active thigh muscles. low-load resistance training low-load resistance training Group of patients that performed exercise training against low mechanical resistance (workload) with sham blood flow restriction (SHAM-BFR) in the active thigh muscles.
- Primary Outcome Measures
Name Time Method Quadriceps muscle isometric strength 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 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 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 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 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).
- Secondary Outcome Measures
Name Time Method knee and muscle pain during each training session, 3-times per week, for 4 weeks The intensity of pain at rest and at the end of each exercise repetition was rated using a numerical pain scale (NPRS) from 0-10, with 0 is the absence of pain and 10 is the worst pain imaginable.
ratings of perceived exertion during each training session, 3-times per week, for 4 weeks Ratings of perceived exertion (RPE) were assessed at the end of each exercise set using the Borg 10 category-ratio scale, with 0 is no effort and 10 is an extreme physical effort.
Trial Locations
- Locations (2)
University of Primorska, Faculty of Health Sciences
🇸🇮Izola, Slovenia
University of Ljubljana, Faculty of Health Sciences
🇸🇮Ljubljana, Slovenia