Sarcopenia, a syndrome commonly seen in elderly populations, is often characterized by a gradual loss of skeletal muscle, leading to the decline of muscle strength and physical performance. Growing evidence suggests that the prevalence of sarcopenia increases in patients with heart failure (HF), which is a dominant pathogenesis in the aging heart. HF causes diverse metabolic complications that may result in sarcopenia. Therefore, sarcopenia may act as a strong predictor of frailty, disability, and mortality associated with HF. Currently, standard treatments for slowing muscle loss in patients with HF are not available. Therefore, here, we review the pathophysiological mechanisms underlying sarcopenia in HF as well as current knowledge regarding the beneficial effects of exercise on sarcopenia in HF and related mechanisms, including hormonal changes, myostatin, oxidative stress, inflammation, apoptosis, autophagy, the ubiquitin-proteasome system, and insulin resistance.

Purpose: Fat browning contributes to energy consumption and may have metabolic benefits against obesity; however, the potential roles of lactate and β-hydroxybutyrate (β-HB) in fat browning remain unclear. We investigated the roles of a single bout of aerobic exercise that increases lactate and β-HB levels in the fasted state on the regulation of fat browning in rats and humans. Methods: Male Sprague–Dawley rats were exposed to 24-h fasting and/or a single bout moderate-intensity aerobic exercise (40 min): sedentary (CON), exercise (ND-EX), fasting (FAST), and exercise + fasting (F-EX). Adult men (n = 13) were randomly assigned into control with food intake (CON), exercise with intensity at onset of blood lactate accumulation in the fasted state (F-OBLA), and high-intensity interval exercise in the fasted state (F-HIIE) until each participant expended 350 kcal of energy. For evaluating the effects of exercise intensity in rats, we conducted another set of animal experiment, including groups of sedentary fed control, fasting control, and exercise with moderate-intensity or HIIE for 40 min after a 24-h fasting. Results: Regardless of fasting, single bout of exercise increases the concentration of lactate and β-HB in rats, but the exercise in the fasted state increases the β-HB level more significantly in rats and humans. F-EX-activated fat browning (AMPK–SirT1–PGC1α pathway and PRDM16) and thermogenic factor (UCP1) in white fat of rats. In rats and humans, exercise in the fasted state increased the blood levels of fat browning–related adipomyokines. In particular, compared with F-OBLA, F-HIIE more efficiently increases free fatty acid as well as blood levels of fat browning adipomyokines in humans, which was correlated with blood levels of lactate and β-HB. In rats that performed exercise with different intensity, the higher plasma lactate and β-HB levels, and higher expression of p-AMPK, UCP1, and PRDM16 in white adipose tissue of HIIE group than those of moderate-intensity group, were observed. Conclusions: A single bout of aerobic exercise in the fasted state significantly induced fat browning–related pathways, free fatty acid, and adipomyokines, particularly F-HIIE in human. Although further evidence for supporting our results is required in humans, aerobic exercise in the fasted state with high intensity that increase lactate and β-HB may be a modality of fat browning.

Background: Although several equations for predicting VO_2max in children and adolescents have been reported, the validity of application of these equations to the Korean population has not been verified. The purpose of study was to develop and validate regression models to estimate maximal oxygen uptake (VO_2max) using a newly developed 20 m progressive shuttle test (20 m PST) protocol in Korean male (n = 80, 15.3 ± 1.86 years) and female (n = 81, 15.5 ± 1.73 years) adolescents aged 13–18 years. Methods: The modified 20 m PST was performed and the VO_2max was assessed in a sample of 161 participants. The participants underwent a treadmill test (TT) in the laboratory and the modified 20 m PST in a gymnasium. For the validation study, the participants performed the TT with a stationary metabolic cart and the 20 m PST with a portable metabolic cart once. In addition, they performed the 20 m PST two more times to establish test–retest reliability. Results: The mean VO_2max (49.6 ± 8.7 mL·kg⁻¹·min⁻¹) measured with the potable metabolic cart was significantly higher than that measured in the graded exercise test with the stationary metabolic cart (46.6 ± 8.9 mL·kg⁻¹·min⁻¹, p < 0.001) using the new 20 m PST protocol. The standard error of the estimate (SEE) between these two measurements was 1.35 mL·kg⁻¹·min⁻¹. However, the VO_2max derived from the newly developed equation was 46.7 ± 7.3 mL·kg⁻¹·min⁻¹ (p > 0.05) and the SEE was 2.90 mL·kg⁻¹·min⁻¹. The test and retest trials of the 20 m PST yielded comparable results (laps, r = 0.96; last speed, r = 0.93). Conclusions: Our data suggest that the new 20 m PST protocol is valid and reliable and that the equation developed in this study provides a valid estimate of VO_2max in Korean male and female adolescents aged 13–18 years.

PURPOSE: To investigate the effect of a 4-week training using a laboratory index on the competition record of elite female middle-distance runners.METHODS: A female, middle-distance, trained runner with the following characteristics: age, 20 years; height, 168.7 cm; weight, 64.3 kg; 27.2% fat; and VO2max, 56.4 VO2 mL/kg/min; volunteered to participate in this study. Before the training program, the participant took part in a 1,500-m track and field national event in April and the onset of blood lactate threshold was analyzed using (OBVA/ vOBLA), VO2max/vVO2max, and tVO2max tests. After completing the 4-week training program, the participant again took part in the 1,500-m track and field national event in May and her parameters were reassessed using the OBVA/vOBLA, VO2max/vVO2max, and tVO2max tests.RESULTS: Pre- and post-training indicate that vVO2max did not improve; however, tVO2max (206 seconds pre-training vs. 251.51 seconds post-training) and VO2max (56.4 vs. 59.3 VO2 mL/kg/min)significantly. However, this improvement in relative VO2 was due to weight loss, and the absolute value of VO2 (3.63 vs. 3.62 L/min) did not change. The 1,500-m race record in track and field events decreased significantly from a pre-training value of 5 minutes 03 seconds to a post-training value of 4 minutes 52 seconds. CONCLUSIONS: The results of this study indicate that utilizing laboratory indicators including vOBLA, vVO2max, and tVO2max may be extremely valuable when prescribing training programs for middle-distance runners.

PURPOSE: Leukocyte telomere length (LTL) is a potential indicator of cellular senescence. However, its relationship with the type and volume of regular exercise is unclear. Therefore, we investigated the effects of the type and volume of long-term regular exercise on the LTL in middle-aged men (N=109, mean age=44.7±4.1 years [range: 40-56 years]).METHODS: For all participants, the volume of physical activity (PA) was evaluated using a self-report questionnaire, and blood samples were collected simultaneously. We cross-sectionally examined the associations among the type and volume of PA, LTL, telomerase activity (TA), mitochondrial DNA copy number (mtDNA), and body composition in three groups: 1) bodybuilders (BBs) with at least 5 years of athletic experience (n=36, mean age: 42.3±3.3 years [40-51 years]), 2) cyclists (CCs) with an athletic career similar to that of the BBs (n=37, mean age: 45.4±4.4 years [range: 40-53 years]), and 3) healthy ordinary people (CON; n=36, mean age: 46.3±3.3 years [range: 40-56 years]).RESULTS: The LTL showed a significant positive correlation with the volume of PA (r=.285, p=.003), regardless of the type of PA. Furthermore, the LTLs were longer in the BB (p=.007) and CC (p=.003) groups (who performed moderate-to-vigorous PA for 150 minutes or more per week) than in the CON group. Conversely, the TA was significantly higher in the BB group (p=.009) than in the CON group; however, it only tended to be high in the CC group (p=.115). There were no intergroup differences in both the mtDNA (p=.127) and 8-hydroxydeoxyguanosine (p=.289) levels.CONCLUSIONS: The TA was found to increase, and thus prevent telomere loss, in middle-aged men who performed PA of moderateto-vigorous intensity, regardless of the PA type.

PURPOSE: To evaluate the effects of resistance exercise with intermittent blood flow restriction (BFR) on the muscle thickness, maximal strength, and isokinetic muscular function (strength, power, endurance) in high school field hockey athletes.METHODS: The BFR group (n=10, 16.1±1.1 years, 172.8±3.9 cm, 66.2±3.9 kg) and the control (CON) group (n=10, 16.60±1.17 years, 172.5±2.3 cm, 65.7±2.9 kg) participated in the same nonlinear periodic training program, however different weight loading (%RM) was applied depending on whether or not BFR was applied. In this study, the systolic blood pressure was set as the blood flow compression strength, and a BFR prop belt was used. After the 8-week training period was over, the degree of improvement in body composition, 1 repetition maximum (1RM), and isokinetic muscle function among groups was compared to determine the effect of training by blood flow restriction.RESULTS: The cross-sectional area of the thighs of athletes who applied BFR was significantly increased than that of the CON (p<.05). In the isokinetic results, athletes with BFR showed higher 1RM than the CON (p<.05). but there were no differences in muscle power and endurance (p>.05). In the results of improving the muscle strength (1RM and 60º/sec) of the athletes who applied the BFR, there was no significant difference between the groups in muscle power and muscular endurance.CONCLUSIONS: Non-linear strength training with BFR might be considered to be an effective method for improving muscle hypertrophy and maximum strength of athletes. The muscle endurance and muscle power method once a week, which was not effective in improving the muscle power and muscular endurance of high school male hockey players.