Wild watermelon contains various nutrients, but the effect of its acute ingestion on arterial stiffness is unclear. This study aimed to investigate whether a single bout of acute ingestion of wild watermelon-extracted juice decreased arterial stiffness concomitant with an increase in nitric oxide (NO) production. Twelve healthy young female participants were tested under two conditions in a randomized, double-blind crossover study: (1) a beverage containing 90 g of wild watermelon extract and (2) a control beverage: a placebo. Pulse wave velocity (PWV), an index of arterial stiffness, blood flow, and plasma nitrate/nitrite (NOx) levels were measured in the supine position at 30, 60, and 90 min after the intake of each beverage. The changes in femoral-ankle PWV were significantly reduced after wild watermelon-extracted juice intake compared to those in the placebo group. Additionally, the changes in blood flow in the posterior tibial artery and plasma NOx levels after intake of wild watermelon-extracted juice were significantly increased compared to those in the placebo group. These data show that acute ingestion of wild watermelon-extracted juice reduces peripheral (lower limb) arterial stiffness and increases NO bioavailability. To confirm these associations, more detailed investigations of the nutrients that influence these effects should be conducted.

Chronic Chlorella intake and aerobic exercise training reduce arterial stiffness and increase circulating nitric oxide (NO) levels, which has beneficial effects. This study aimed to clarify the combined aortic NO-mediated effects of chronic Chlorella intake and aerobic exercise training on endothelial vasorelaxation in aged mice. In this study, 38-week-old male senescence-accelerated mouse prone 1 (SAMP1) mice were divided into aged sedentary control (Con), aerobic exercise training (AT; voluntary wheel running for 12 weeks), Chlorella intake (CH; 0.5% Chlorella powder in normal diet), and AT and CH combined (AT+CH) groups. Endothelium-dependent vasorelaxation by addition of acetylcholine to the isolated mouse aortic rings was significantly higher in the AT, CH, and AT+CH groups than in the Con group; a significantly greater effect was seen in the AT+CH group than in the AT and CH groups. Similarly, plasma and arterial nitrite/nitrate levels and arterial endothelial NO synthase phosphorylation were significantly higher in the AT, CH, and AT+CH groups than in the Con group; the AT+CH group had higher values than the AT and CH groups. Thus, chronic Chlorella intake combined with aerobic exercise training had pronounced effects on endothelial vasorelaxation in aged mice via an additive increase in arterial NO production. Novelty: Endothelium-dependent vasorelaxation was improved by Chlorella intake and exercise. Chlorella intake and exercise increased arterial Akt/eNOS/NO signaling. This combination approach further improved vasorelaxation via arterial NO production.

Resistance training and Dioscorea esculenta intake have a positive effect on muscle. Therefore, we aimed to determine whether 12-week Dioscorea esculenta intake combined with resistance exercise more effectively improves muscle quantity, quality, and cardiometabolic parameters in healthy middle-aged and older adults. This study is a double-blind trial with 66 volunteers (21 males/45 females; age 53 ± 5 years; body weight 61 ± 11 kg; BMI 24 ± 4 kg) who were randomly divided into four groups: sedentary-control with placebo (Sed and PL) or Dioscorea (Sed and Dio) and resistance training with placebo (RT and PL) or Dioscorea (RT and Dio). Resistance training sessions using elastic bands were performed 3 days/week for a 12-week period. Dioscorea esculenta tablets were ingested at 2000 mg/day once per day. The RT and Dio group showed greater improvements in the femoris muscle’s thickness, echo intensity for the rectus femoris (index of muscle quality), and the five times sit-to-stand test compared to that of the Sed and PL group; the echo intensity in the RT and Dio group further improved compared to those in the Sed and Dio, and RT and PL groups (p < 0.05). The circulating levels of C1q (a potential biomarker of muscle fibrosis) in the RT and Dio group were significantly lower than those in the Sed and PL, and Sed and Dio groups (p < 0.05). Chronic Dioscorea esculenta intake combined with low-intensity resistance exercise may more effectively improve muscle quantity and quality indices in healthy middle-aged and older adults.

Purpose: Recent studies have reported positive cardiometabolic responses when prolonged sitting is broken up with brief, bursts of vigorous activity termed “exercise snacks”. However, the mechanism underlying the potential health benefits of exercise snacks remain unstudied. Exercise-induced muscle contractions can promote the release of myokines that contribute to muscle remodeling and systemic cardiometabolic adaptations through inter-organ signaling. This study aimed to profile the effects of stair-climbing exercise snacks on secretion of six established myokines in young normal-weight males and adults living with overweight or obesity. Methods: In two separate randomized crossover studies, 11 young normal-weight men (NW; study 1) and 8 adults with overweight/obesity (OW; study 2) completed two experimental conditions: (i) sedentary (SED; 9-h sitting) and (ii) exercise snacks (SS; 15–30 s stair-climbing once per hour). The same high-glycemic index meals were consumed at 0, 3, and 6 h at each condition. The primary outcome was the changes in circulating myokines levels before and after the 9-h. Results: Changes in circulating apelin levels from baseline to 9-h were higher in the SS condition compared to SED in both NW (SS: 102.2 ± 223.7 pg/mL, SED: -59.9 ± 131.6 pg/mL; P < 0.05) and OW (SS: 46.4 ± 85.3 pg/mL, SED: -120.3 ± 194.2 pg/mL; P < 0.05) groups, with no apparent difference between groups. Plasma concentration of other myokines remained unchanged across 9-h in SED and SS in both groups. Conclusions: Hourly stair-climbing exercise snacks did not induce clear alterations in most measured myokines, whereas apelin levels were elevated across the day compared with prolonged sitting in both groups.

Background: Chronic chlorella intake combined with high-intensity intermittent training (HIIT) has been shown to accelerate aerobic and anaerobic capacities in rodents. This study aimed to clarify the effects of combining chlorella intake with short-term HIIT on exercise performance in humans, and to investigate the impact of chlorella intake on cardiac adaptation. Materials and Methods: In Study 1, twelve healthy young men completed a 3-week exhaustive HIIT, comprising 6–7 bouts of 20 s of cycling on a leg ergometer at an intensity of 170% maximal oxygen uptake ($\dot{\mathrm{V}}$O_2max), with a 10 s rest between each bout, 3 days/week. They were orally administered either placebo or chlorella during the 3 weeks in a double-blinded, randomized crossover trial (RCT). In Study 2, six healthy young men were orally administered either placebo or chlorella during 4 weeks in a double-blinded, placebo-controlled RCT. We measured $\dot{\mathrm{V}}$O_2max and cardiac function (stroke volume [SV], heart rate [HR], and cardiac output [CO]) during maximal exercise. In Study 3, chlorella-induced changes in molecular markers of maladaptation of the heart were measured in healthy rats. Results: [Study 1] After each HIIT, $\dot{\mathrm{V}}$O_2max significantly increased in the placebo and chlorella groups (p < 0.05). Changes in $\dot{\mathrm{V}}$O_2max were significantly higher in the chlorella group than in the placebo group (p < 0.05). [Study 2] Changes in SV and CO during maximal exercise were significantly higher in the chlorella group than in the placebo group (p < 0.05 each), but HR_max did not change. [Study 3] Chronic chlorella intake did not change the molecular markers of pathological cardiac hypertrophy. Conclusions: Chronic chlorella intake, which improves aerobic capacity by enhancing cardiac function without causing cardiac maladaptation, combined with short-term HIIT, further enhanced aerobic capacity. Thus, the chlorella-induced increase in cardiac function may further enhance aerobic capacity through HIIT.

This study aimed to assess the effect of a combination of aerobic exercise training (ET) and Chlorella (CH) intake on arterial nitric oxide (NO) production and arterial stiffness in obese rats. Twenty-week-old obese male rats were randomly grouped into four (n = 6): OBESE-SED (sedentary control), OBESE-ET (treadmill 25 m/min, 1 h, 5 d/week), OBESE-CH (0.5% Chlorella powder in normal diet), and OBESE-ET+CH (combination of ET and CH intake) groups. The carotid–femoral pulse wave velocity (cfPWV), an index of arterial stiffness, was significantly lesser in the OBESE-ET, OBESE-CH, and OBESE-ET+CH groups than in the OBESE-SED group, and in the OBESE-ET+CH group significantly further enhanced these effects compared with the OBESE-ET and OBESE-CH groups. Additionally, arterial nitrate/nitrite (NOx) levels were significantly greater in the OBESE-ET, OBESE-CH, and OBESE-ET+CH groups than in the OBESE-SED group, and the OBESE-ET+CH group compared with the OBESE-ET and OBESE-CH groups. Furthermore, arterial NOx levels were positively correlated with arterial endothelial NO synthase phosphorylation levels (r = 0.489, p < 0.05) and negatively correlated with cfPWV (r = −0.568, p < 0.05). In conclusion, a combination of ET and CH intake may reduce arterial stiffness via an enhancement of the arterial NO signaling pathway in obese rats.