ADAPTations to low load blood flow restriction exercise versus conventional heavier load resistance exercise in UK military personnel with persistent knee pain: protocol for the ADAPT study, a multi-centre randomized controlled trial.

BACKGROUND: Muscle atrophy, muscle weakness and localised pain are commonly reported following musculoskeletal injury (MSKI). To mitigate this risk and prepare individuals to return to sport or physically demanding occupations, resistance training (RT) is considered a vital component of rehabilitation. However, to elicit adaptations in muscle strength, exercise guidelines recommend lifting loads ≥ 70% of an individual's one repetition maximum (1-RM). Unfortunately, individuals with persistent knee pain are often unable to tolerate such high loads and this may negatively impact the duration and extent of their recovery. Low load blood flow restriction (LL-BFR) is an alternative RT technique that has demonstrated improvements in muscle strength, hypertrophy, and pain in the absence of high mechanical loading. However, the effectiveness of high-frequency LL-BFR in a residential rehabilitation environment remains unclear. This study will compare the efficacy of high frequency LL-BFR to 'conventional' heavier load resistance training (HL-RT) on measures of physical function and pain in adults with persistent knee pain. METHODS: This is a multicentre randomised controlled trial (RCT) of 150 UK service personnel (aged 18-55) admitted for a 3-week residential rehabilitation course with persistent knee pain. Participants will be randomised to receive: a) LL-BFR delivered twice daily at 20% 1-RM or b) HL-RT three-times per week at 70% 1-RM. Outcomes will be recorded at baseline (T1), course discharge (T2) and at three-months following course (T3). The primary outcome will be the lower extremity functional scale (LEFS) at T2. Secondary outcomes will include patient reported perceptions of pain, physical and occupational function and objective measures of muscle strength and neuromuscular performance. Additional biomechanical and physiological mechanisms underpinning both RT interventions will also be investigated as part of a nested mechanistic study. DISCUSSION: LL-BFR is a rehabilitation modality that has the potential to induce positive clinical adaptations in the absence of high mechanical loads and therefore could be considered a treatment option for patients suffering significant functional deficits who are unable to tolerate heavy load RT. Consequently, results from this study will have a direct clinical application to healthcare service providers and patients involved in the rehabilitation of physically active adults suffering MSKI. TRIAL REGISTRATION: ClinicalTrials.org reference number, NCT05719922.

The effect of pre-cooling or per-cooling in athletes with a spinal cord injury: A systematic review and meta-analysis.

OBJECTIVES: For individuals with a spinal cord injury, thermoregulatory challenges presented by the environment are amplified, increasing the risk of exertional heat illness. Thus, this systematic review and meta-analysis aims to quantify the effects of pre- and per-cooling on core temperature (Tc), skin temperature (Tsk) and thermal sensation in participants with spinal cord injury and assess the influence of lesion level on the effects of cooling. DESIGN: Systematic review with meta-analysis. METHODS: Out of 2107 potential studies, 17 were identified via the inclusion criteria for a total of 145 research participants. A total of 12 studies were included in the primary analysis of Tc; 9 included in the analysis of Tsk; and 9 included in the analysis of thermal perceptions. 15 experimental conditions were included in the secondary analysis of lesion level on the effects of cooling. RESULTS: Cooling reduced Tc (Hedges' g = 0.44; 95% confidence intervals 0.16, 0.72; p < 0.001), Tsk (Hedges' g = 1.11; 95% confidence intervals 0.56, 1.66; p < 0.002) and thermal sensation (Hedges' g = 0.60; 95% confidence intervals 0.27, 0.93; p < 0.001). Subgroup analysis revealed pre-cooling (Hedges' g = 0.92), reduced Tc to a greater extent than per-cooling (Hedges' g = 0.25; p = 0.020). The effect of lesion level on the effectiveness of cooling on Tc had a moderate, positive association (r = 0.518, p = 0.048). CONCLUSION: Pre-cooling may reduce Tc to a greater extent than per-cooling during subsequent exercise. Pre- and per-cooling can attenuate the increase in thermal strain in athletes with a spinal cord injury. The beneficial effects of cooling are greater in tetraplegic individuals.