Effect of New Zealand Blackcurrant Extract on Isometric Contraction-Induced Fatigue and Recovery: Potential Muscle-Fiber Specific Effects

CHINESE MEDICINAL BATH ON ATHLETES’ SPORT MUSCLE FATIGUE

ABSTRACT Introduction: The Fifth International Conference on Sports Biochemistry defines sports fatigue as the physiological process of dysfunction at a certain level or inability to maintain predetermined exercise intensity. When left untreated, it can cause adverse effects to the musculoskeletal system. Natural alternatives for controlling sports fatigue exist in Chinese culture, but scientific research is needed to determine the effectiveness of these treatments. Objective: This study aimed to verify the effect of traditional Chinese medicinal baths on athletes’ muscle fatigue. Methods: 100 athletes with exercise-induced muscle fatigue were randomly divided into two groups. The control group received ganglioside injection combined with therapeutic exercise protocols, while the experimental group received the medicinal bath based on traditional Chinese medicine. Tonus of adductors, ischiotibials, gastrocnemius, in addition to lower limb motor function, was evaluated. Results: The total effective rate (90.8%) of the observation group was higher than that of the control group (72.3%), and the difference was statistically significant (P<0.05). After treatment, adductor, hamstring, and gastrocnemius muscle tension in the observation group were lower than the control group (P<0.05). Gross motor function assessment score (GMFM-88), Berg Balance Scale (BBS), 10m walking speed on a 20cm wide walkway (MWS) in the observation group were higher than those in the control group (P<0.05). Conclusion: Chinese herbal lavender lotion combined with suspension exercise can effectively improve the body's muscle strength after exercises, accelerate the recovery of muscle strength, and significantly reduce exercise-induced muscle fatigue. Evidence Level II; Therapeutic Studies - Investigating the result.

Effect of New Zealand Blackcurrant Extract on Force Steadiness of the Quadriceps Femoris Muscle during Sustained Submaximal Isometric Contraction

Intake of anthocyanin-rich New Zealand blackcurrant (NZBC) can alter physiological responses that enhance exercise performance. In two studies, we examined the effects of NZBC extract on force steadiness during a sustained submaximal isometric contraction of the quadriceps femoris muscle. With repeated measures designs, male participants in study one (n = 13) and study two (n = 19) performed a 120 s submaximal (30%) isometric contraction of the quadriceps femoris muscle following a 7-day intake of NZBC extract and placebo (study one) and following 0 (control), 1-, 4- and 7-day intake of NZBC extract (study two). Participants for both studies were different. In study one, NZBC extract enhanced isometric force steadiness during the 120 s contraction (placebo: 6.58 ± 2.24%, NZBC extract: 6.05 ± 2.24%, p = 0.003), with differences in the third (60-89 s) and fourth quartile (90-120 s) of the contraction. In study two, isometric force steadiness was not changed following 1 and 4 days but was enhanced following 7-day intake of NZBC extract in comparison to control. In study two, the enhanced isometric force steadiness following 7-day intake did occur in the second (30-59 s), third (60-89 s) and fourth (90-120 s) quartiles. Daily supplementation of anthocyanin-rich NZBC extract can enhance force steadiness of the quadriceps femoris muscle during a sustained submaximal isometric contraction. Our observations may have implications for human tasks that require postural stability.

Effect of Intake Duration of Anthocyanin-Rich New Zealand Blackcurrant Extract on Cardiovascular Responses and Femoral Artery Diameter during Sustained Submaximal Isometric Contraction

Seven-day intake of anthocyanins from New Zealand blackcurrant (NZBC) extract increased cardiac output and femoral artery diameter during a sustained submaximal isometric contraction. It is not known if there are intake duration effects by NZBC extract on the isometric contraction-induced cardiovascular responses. In a repeated measures design, male participants (n = 19, age: 26 ± 4 years) performed a 120-second submaximal (30%) isometric contraction of the knee extensors at baseline and following 1, 4 and 7-days intake of 600 mg·day^-1 NZBC extract. During the 120-second submaximal isometric contraction, femoral artery diameter and cardiovascular responses were measured with ultrasound and beat-to-beat hemodynamic monitoring. Femoral artery was larger following 4-days (mean difference = 0.046 cm, 95% CI [0.012, 0.080], p = 0.005) and 7-days (mean difference = 0.078 cm, 95% CI [0.034, 0.123], p < 0.001) in comparison to baseline with no increase with 1-day intake. Systolic and diastolic blood pressure, heart rate and total peripheral resistance were not changed by NZBC extract at 1, 4 and 7-days intake. However, mean arterial pressure, stroke volume, cardiac output and total peripheral resistance were changed at time points during the isometric contraction following 7-days intake in comparison to 1-day intake of NZBC extract (p < 0.05). Alterations in femoral artery diameter and some cardiovascular responses during a submaximal sustained isometric contraction of the knee extensors are affected by the intake duration of New Zealand blackcurrant extract, with no effects by 1-day intake. Our observations suggest that the bioavailability of blackcurrant anthocyanins and anthocyanin-derived metabolites is required for days to alter the mechanisms for isometric-contraction induced cardiovascular responses.