Wing Yin Lau

Effect of vibration treatment on symptoms associated with eccentric exercise-induced muscle damage

Objective: The aim of this study was to test the hypothesis that vibration treatment reduces delayed‐onset muscle soreness and swelling and enhances recovery of muscle function after eccentric exercise. Design: A randomized crossover design was used. Fifteen young men performed ten sets of six maximal eccentric contractions of the elbow flexors with the right arm for one occasion and the left arm for the other occasion separated by 4 wks. One arm received a 30‐min vibration treatment at 30 mins after and 1, 2, 3, and 4 days after the exercise (treatment group), and the other arm did not receive any treatment (control group). The order of the treatment and control conditions and the use of the dominant and nondominant arms were counterbalanced among subjects. Changes in indirect markers of muscle damage were compared between arms by a two‐way repeated‐measures analysis of variance. Results: Compared with the control group, the treatment group showed significantly (P < 0.05) less development and faster reduction in delayed‐onset muscle soreness at 2 to 5 days after exercise. The recovery of range of motion was significantly (P < 0.05) faster for the treatment than for the control group. However, no significant effects on the recovery of muscle strength and serum creatine kinase activity were evident. Immediately after the vibration treatment, a significant (P < 0.05) decrease in the magnitude of delayed‐onset muscle soreness and muscle strength and an increase in pressure pain threshold and range of motion were found. Conclusions: These results showed that the vibration treatment was effective for attenuation of delayed‐onset muscle soreness and recovery of range of motion after strenuous eccentric exercise but did not affect swelling, recovery of muscle strength, and serum creatine kinase activity.

Reduced muscle lengthening during eccentric contractions as a mechanism underpinning the repeated-bout effect

This study investigated biceps brachii distal myotendinous junction (MTJ) displacement during maximal eccentric elbow flexor contractions to test the hypothesis that muscle length change would be smaller (less MTJ displacement) during the second than the first exercise bout. Ten untrained men performed two eccentric exercise bouts (ECC1 and ECC2) with the same arm consisting of 10 sets of six maximal isokinetic (60°/s) eccentric elbow flexor contractions separated by 4 wk. Biceps brachii distal MTJ displacement was assessed using B-mode ultrasonography, and changes in the displacement (muscle length change) from the start to the end of each contraction during each set and over 10 sets were compared between bouts by two-way repeated-measures ANOVA. Several indirect muscle damage markers were also measured and compared between bouts by two-way repeated-measures ANOVA. The magnitude of MTJ displacement (average of six contractions) increased from set 1 (8.2 ± 4.7 mm) to set 10 (16.4 ± 4.7 mm) during ECC1 (P < 0.05), but no significant changes over sets were evident during ECC2 (set 1: 8.5 ± 4.0 mm; set 10: 9.3 ± 3.1 mm). Changes in maximal voluntary isometric contraction strength, range of motion, muscle thickness, ultrasound echo intensity, serum creatine kinase activity, and muscle soreness (visual analog scale) were smaller (P < 0.05) following ECC2 than ECC1, showing less damage in the repeated bout. These results indicate that the magnitude of muscle lengthening was less during the second than the first eccentric exercise bout, which appears to be a mechanism underpinning the repeated-bout effect.

Visual Analog Scale and Pressure Pain Threshold for Delayed Onset Muscle Soreness Assessment

Abstract Objectives: To investigate the relationship between two assessments to quantify delayed onset muscle soreness [DOMS]: visual analog scale [VAS] and pressure pain threshold [PPT]. Methods: Thirty-one healthy young men [25.8 ± 5.5 years] performed 10 sets of six maximal eccentric contractions of the elbow flexors with their non-dominant arm. Before and one to four days after the exercise, muscle pain perceived upon palpation of the biceps brachii at three sites [5, 9 and 13 cm above the elbow crease] was assessed by VAS with a 100 mm line [0 = no pain, 100 = extremely painful], and PPT of the same sites was determined by an algometer. Changes in VAS and PPT over time were compared amongst three sites by a two-way repeated measures analysis of variance, and the relationship between VAS and PPT was analyzed using a Pearson product-moment correlation. Results: The VAS increased one to four days after exercise and peaked two days post-exercise, while the PPT decreased most one day post-exercise and remained below baseline for four days following exercise [p < 0.05]. No significant difference among the three sites was found for VAS [p = 0.62] or PPT [p = 0.45]. The magnitude of change in VAS did not significantly correlate with that of PPT [r = −0.20, p = 0.28]. Conclusion: These results suggest that the level of muscle pain is not region-specific, at least among the three sites investigated in the study, and VAS and PPT provide different information about DOMS, indicating that VAS and PPT represent different aspects of pain.

Assessment of Muscle Pain Induced by Elbow-Flexor Eccentric Exercise

CONTEXT Delayed-onset muscle soreness (DOMS) is a common muscle pain that many people experience and is often used as a model of acute muscle pain. Researchers have reported the effects of various interventions on DOMS, but different DOMS assessment protocols used in these studies make it difficult to compare the effects. OBJECTIVE To investigate DOMS characteristics after elbow-flexor eccentric exercise to establish a standardized DOMS assessment protocol. DESIGN Descriptive laboratory study. SETTING Research laboratory. PATIENTS OR OTHER PARTICIPANTS Ten healthy, untrained men (21-39 years). INTERVENTION(S) Participants performed 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors. MAIN OUTCOME MEASURE(S) Indirect muscle-damage markers were maximal voluntary isometric contraction torque, range of motion, and serum creatine kinase activity. Muscle pain was assessed before exercise, immediately postexercise, and 1 to 5 days postexercise using (1) a visual analog scale (VAS), (2) a category ratio-10 scale (CR-10) when applying static pressure and palpation at different sites (3, 9, and 15 cm above the elbow crease), and (3) pressure-pain thresholds (PPTs) at 50 sites (pain mapping). RESULTS Maximal voluntary isometric contraction and range of motion decreased and creatine kinase activity increased postexercise, indicating muscle damage. Palpation induced greater pain than static pressure, and longitudinal and transverse palpations induced greater pain than circular palpation (P < .05). The PPT was lower in the medial region before exercise, but the pain-sensitive regions shifted to the central and distal regions of the biceps brachii at 1 to 3 days postexercise (P < .05). The VAS was correlated with the CR-10 scale (r = 0.91, P < .05) but not with the PPT (r = -0.28, P = .45). CONCLUSIONS The way in which muscles are assessed affects the pain level score. This finding suggests that pain level and pain threshold cannot be used interchangeably and that the central and distal regions of the biceps brachii should be included in DOMS assessment using the VAS, CR-10 scale, and PPT after elbow-flexor eccentric exercise.

Improvement of Sprint Triathlon Performance in Trained Athletes With Positive Swim Pacing.

PURPOSE To investigate the effect of 3 swim-pacing profiles on subsequent performance during a sprint-distance triathlon (SDT). METHODS Nine competitive/trained male triathletes completed 5 experimental sessions including a graded running exhaustion test, a 750-m swim time trial (STT), and 3 SDTs. The swim times of the 3 SDTs were matched, but pacing was manipulated to induce positive (ie, speed gradually decreasing from 92% to 73% STT), negative (ie, speed gradually increasing from 73% to 92% STT), or even pacing (constant 82.5% STT). The remaining disciplines were completed at a self-selected maximal pace. Speed over the entire triathlon, power output during the cycle discipline, rating of perceived exertion (RPE) for each discipline, and heart rate during the cycle and run were determined. RESULTS Faster cycle and overall triathlon times were achieved with positive swim pacing (30.5 ± 1.8 and 65.9 ± 4.0 min, respectively), as compared with the even (31.4 ± 1.0 min, P = .018 and 67.7 ± 3.9 min, P = .034, effect size [ES] = 0.46, respectively) and negative (31.8 ± 1.6 min, P = .011 and 67.3 ± 3.7 min, P = .041, ES = 0.36, respectively) pacing. Positive swim pacing elicited a lower RPE (9 ± 2) than negative swim pacing (11 ± 2, P = .014). No differences were observed in the other measured variables. CONCLUSIONS A positive swim pacing may improve overall SDT performance and should be considered by both elite and age-group athletes during racing.

Increases in biceps brachii fascia thickness after eccentric exercise of the elbow flexors

BACKGROUND Unaccustomed eccentric exercise induces muscle damage characterised by delayed onset of muscle soreness (DOMS) and prolonged loss of muscle function, but confers protective effect against the same exercise performed within several weeks, known as the repeated bout effect. The mechanisms underpinning the repeated bout effect are not fully understood, but changes in muscle-tendon behaviour seem to be one of them. It is possible that anatomical changes in muscle fascia are associated with the repeated bout effect. The present study investigated changes in biceps brachii muscle fascia thickness after eccentric exercise of the elbow flexors.