Search

Previous research has suggested that the addition of blood flow restriction (BFR) to dynamic exercise increases the magnitude of post-exercise hypoalgesia. However, it is unknown if the addition of BFR to low intensity isometric handgrip exercise would elicit any additional exercise-induced hypoalgesic effect. PURPOSE: To examine the effect of isometric handgrip exercise in combination with BFR on exercise-induced hypoalgesia at local and non-local muscles. METHODS: 60 participants performed 3 experimental trials: isometric handgrip exercise (ISO) at 30% of maximum handgrip strength; isometric handgrip exercise with BFR at 50% of resting arterial occlusion pressure (ISO+BFR); and time-matched non-exercising control (CON). The exercise involved 4 sets of isometric handgrip exercise with each set lasting 2-min. 1-min rest intervals separated each set. Pressure pain thresholds were assessed at pre, after each set, and 5 -min post exercise at local and non-local muscle. A Bayesian repeated measures ANOVA was used to examine if the exercise-induced hypoalgesia changed differently between conditions over time. RESULTS: There was an interaction (condition*time) for pressure pain threshold at local (BFinclusion=11236.88) and non-local muscle (BFinclusion=6.49) sites. At the local site, post-hoc comparisons on the change scores indicated that the conditions differed in pressure pain threshold following set 1 (BF10=2.23e+9), set 2 (BF10=6.19e+9), set 3 (1.57e+13), set 4 (2.21e+10), and 5-min post exercise (BF10=18107.48). Pain thresholds were increased in both exercise conditions relative to a CON (~0.45 kg/cm² for ISO, ISO+BFR vs. ~-0.04 kg/cm² for CON). At the non-local site, conditions differed in pain thresholds following set 1 (BF10=1.188e+8), set 2 (BF10=201949.62), set 3 (BF10=1.17e+8), set 4 (BF10=2.27e+6), and 5-min post (BF10=32925.19). Similarly, increased pain threshold was observed at the non-local site in both exercise conditions relative to a CON (~0.37 kg/cm² for ISO, ISO+BFR vs. ~--0.16 kg/cm² for CON). CONCLUSIONS: Performing an acute bout of isometric handgrip exercise with or without BFR can provide exercise-induced hypoalgesia. The addition of BFR to exercise does not provide any additional hypoalgesic effect. [ABSTRACT FROM AUTHOR]

Blood flow restricted exercise results in greater discomfort compared to the same exercise without blood flow restriction. However, this has only been investigated post exercise and it is possible that intra-set discomfort may differ compared with resting discomfort. No study has investigated discomfort during blood flow restricted exercise. Additionally, discomfort with isometric blood flow restricted exercise has not been investigated. PURPOSE: To investigate discomfort and changes in force to isometric exercise with and without blood flow restriction. METHODS: 60 participants (21 males, 39 female; 18-35 years old), completed 2 experimental visits. For both conditions, the participants performed four sets of two minute isometric handgrip contractions, with one minute of rest intervals, at 30% of their maximal voluntary contraction. Discomfort ratings (0-100) were given one minute into the exercise set. For the blood flow restriction condition a 12cm nylon cuff was placed at the most proximal position on the individuals' dominant arm and inflated to 50% of the pressure needed to occlude blood flow. Average force was recorded for each set. To assess differences in discomfort and force we conducted a Bayesian repeated measures ANOVA (condition by time) (prior=.5). RESULTS: There was no evidence for or against an interaction (BF10=.435) for discomfort. There was evidence for an effect of condition (BF10=215.29) and time (BF10=8.006e+13). Blood flow restriction induced greater feelings of discomfort compared to isometric exercise alone (40.5 vs. 35.7 AU respectively). Discomfort increased with subsequent sets. There was evidence against an interaction for differences in force (BF10=.025). There was a main effect of time with force declining across sets, but no main effect of condition. Average force for both conditions was 12.1, 11.3, 10, and 9.6 kg for sets 1, 2, 3, and 4 respectively. CONCLUSIONS: Our results suggest that isometric exercise with blood flow restriction causes greater discomfort during exercise. This difference appears independent to changes in force. Further restriction of venous return by blood flow restriction may increase metabolite build up more than unrestricted exercise, causing greater discomfort. [ABSTRACT FROM AUTHOR]

Downhill running exercises not only induce muscle damage on lower limb muscles, they may also influence upper limb muscle functions and performance. PURPOSE: To examine the relationships between knee extensor muscle soreness and elbow flexor muscle central and peripheral neuromuscular indices following a 1-hour downhill running exercise. METHODS: Seventeen adults (9 in the Control Group: sat and rested for 30 minutes; 8 in the Running Group: ran for 1 hour on a treadmill with a 10% decline) completed this study. Before (Pre), immediately (Post), 24 hours (Post24), and 48 hours (Post48) after the Running or Control, dependent variables (knee extensor muscle soreness, elbow flexion isometric strength, and voluntary activation [VA] along with the resting twitch [RT] of the elbow flexor muscles) were measured. The changes (A: Post-Pre; Post24-Pre; Post48-Pre) of all the dependent variables were calculated. Two-way mixed factorial (time [APre-Post vs. APost24-Pre vs. APost48-Pre] x group [Control vs. Running]) analyses of variance were used to examine the potential group differences across time. In addition, bivariate correlation analyses were conducted to examine the correlations between the changes of knee extensor muscle soreness and the changes of elbow flexor central (VA) and peripheral (RT) neuromuscular indices. RESULTS: Knee extensor muscle soreness was significantly greater in the Running than that in the Control following the downhill run (p < 0.001), and remained elevated throughout the entire 48 hours. There was no group difference for the elbow flexion isometric strength or VA. However, there was a main effect for group (p = 0.005) for the elbow flexion RT (time merged %change: Running = -19.6 ± 6.3% vs. Control = 8.7 ± 5.9%). The bivariate correlation showed no significant correlations between the knee extensor muscle soreness increases and the elbow flexor VA changes at both Post24 (p = 0.183) and Post48 (p = 0.223). However, significant correlations were found between the knee extensor muscle soreness increases and the elbow flexion RT %changes at both Post24 (p = 0.041; r = -0.500) and Post48 (p = 0.024; r = -0.543) time points. CONCLUSIONS: The 1-hour downhill running-induced knee extensor muscle soreness influenced the remote upper limb elbow flexor muscles at a peripheral level lasting a prolonged period. [ABSTRACT FROM AUTHOR]