The Short-term Effect of Low-load Resistance Training with Blood-flow Restriction on Somatosensory-evoked Potentials in Healthy Young Adults

The current study will be conducted in the college of health sciences, physiotherapy department, in the medical campus in the University of Sharjah, Sharjah, United Arab Emirates. The study design is a Randomized Crossover Trial, which will include three groups of healthy young adults, each group will use a different cuff widths (small cuff width (5 cm), medium cuff width (12 cm), and large cuff width (18 cm)). Participants in all three groups will undergo three experimental sessions in a random order, which will include the application of a blood flow restriction cuff combined with resistance exercise, the application of a blood flow restriction cuff without resistance exercise, and traditional resistance exercise without a blood flow restriction cuff. During each session, SSEP measurements will be recorded at three time points: before, during, and after the experimental session by stimulating the tibial nerve at the ankle and measuring the SSEP amplitude and latency.

Healthy young adults aged 18-30 years of both genders will be recruited through word of mouth and through social media by sharing the study flyer. Then, they will be screened for their eligibility to participate in the current study. Participants who will meet the eligibility criteria will be asked to provide their consent after the study is explained by filling out the consent form.

Participants will be randomly assigned to one of the three groups: (1) small cuff width (5 cm), (2) medium cuff width (12 cm), and (3) large cuff width (18 cm) by using permuted block randomization method with large, random, and variable block sizes to ensure groups are balanced and selection bias is minimized.

The first experimental session will start by conducting the one repetition maximum (1-RM) test of unilateral knee extension of the dominant leg, in which the dominant side was identified by asking the participants which side they will use to kick a ball. Before conducting the 1-RM test, 5 minutes warm-up on the cycle ergometer at 75W will be done. Calibration of the dynamometer will be done before operating the machine with each participant, then the participant will be positioned on the dynamometer seat comfortably with ensuring the back is supported and the knee is aligned with the axis of rotation. The participant will be asked to complete one successful repetition of knee extension through full range of motion (ROM), with increasing load until the participant can no longer complete full knee extension ROM, 3 minutes of rest will be allowed between attempts until the 1-RM is identified. To eliminate the effect of fatigue after 1-RM test, the first experimental session will always include the application of the BFR cuff without resistance exercise.

For both experimental sessions 2 and 3, the order of exercise condition will be randomly selected, either to be (1) the application of BFR cuff with resistance exercise, or (2) resistance exercise without the application of BFR cuff to decrease the incidence of learning effect. Cuff pressure during the application of BFR will be standardized to 50% of AOP.

The resistance exercise for both experimental sessions 2 and 3 will be exactly similar and will involve four sets of isometric knee extensions at an intensity of 20% of 1-RM with repetitions of 30, 15, 15, and 15 by using the isokinetic dynamometer machine, which has a good to excellent test-retest reliability for knee extension movement with ICC value of 0.95-0.99. To minimize cognitive and neuromuscular fatigue, the experimental sessions will be separated by a minimum of three days (72 hours).

Inclusion criteria

• Participants will be included if they are aged 18-30 years of both genders, with no history of cardiovascular problems or osteo-articular problems in the lower limbs, and if they responded negatively to all items of the Physical Activity Readiness Questionnaire (PAR-Q).
• Participants will be included if they have a body mass index (BMI) less than 25 or non-overweight individuals.
• Use of the long international physical activity questionnaire (L-IPAQ) to ensure all participants have equal physical activity levels.

Exclusion criteria

• Participants will be excluded if they did not meet the inclusion criteria, and if they had a history of deep vein thrombosis (DVT), congenital heart disease, varicose veins, currently pregnant, or any contraindications to exercise.
• Participants will be excluded if they were diagnosed with any neurological disease.
• Participants will be excluded if they have had any musculoskeletal injury in the past 3 months to avoid potential effect on their physical activity levels.