Running interval training combined with blood flow restriction increases maximal running performance and muscular fitness in male runners.

We investigated the effects of 8 weeks (3 days per week) of running interval training (RIT) combined with blood flow restriction (RIT-BFR) on the maximal running performance (RPmax), isokinetic muscle strength, and muscle endurance in athletes. Twenty endurance-trained male runners were pair-matched and randomly assigned to the RIT-BFR and RIT groups. The RIT-BFR group performed RIT (50% heart rate reserve, 5 sets of 3 min each, and 1-min rest interval) with inflatable cuffs (1.3× resting systolic blood pressure), and the RIT group performed the same RIT without inflatable cuffs. RPmax, isokinetic muscle strength, and muscle endurance were assessed at pre-, mid-, and post-training. Compared with the RIT group, the RIT-BFR group exhibited a significantly (p < 0.05) greater increase in RPmax, isokinetic knee extensor and flexor strength, and knee extensor endurance after 24 training sessions. These results suggested that RIT-BFR may be a feasible training strategy for improving muscular fitness and endurance running performance in distance runners.

Running Training Combined With Blood Flow Restriction Increases Cardiopulmonary Function and Muscle Strength in Endurance Athletes.

ABSTRACT: Chen, Y-T, Hsieh, Y-Y, Ho, J-Y, Lin, T-Y, and Lin, J-C. Running training combined with blood flow restriction increases cardiopulmonary function and muscle strength in endurance athletes . J Strength Cond Res 36(5): 1228-1237, 2022-We investigated the effects of 8 weeks (3 d/wk) of running training (RT) combined with blood flow restriction (RT-BFR) on cardiopulmonary function and muscle strength in endurance athletes. Twenty endurance-trained male athletes (19-25 years; 177.6 ± 2.4 cm; 69.0 ± 2.2 kg) were pair matched and randomly assigned to RT-BFR and RT groups. The RT-BFR group performed running sessions (50% heart rate reserve; 3-minute × 5 sets; 1-minute rest interval) with pressure cuffs (1.3 × resting systolic blood pressure), whereas the RT group performed the same running sessions without pressure cuffs. V̇o2max, muscle mass, isokinetic muscle strength, and hormones were assessed at pre-, mid- and posttraining. Compared with the RT group, the RT-BFR group exhibited a significantly greater increase in V̇o2max (5.1 vs. -1.1%) and isokinetic knee extensor strength (16.5 vs. -5.9%). In addition, RT-BFR group presented higher leg muscle mass (10.3 vs. 9.7 kg) than that of RT group after 8 weeks of training. Furthermore, testosterone to cortisol (T:C) ratio at 24 hours after training session at pre-, mid-, and posttraining were maintained in the RT-BFR group, whereas significant decreases of T:C ratio at 24 hours after training session were observed in the RT group. These results suggested that RT combined with BFR may be a practical training strategy for promoting cardiopulmonary function and muscle strength in endurance runners.

Systemic Lactate Elevation Induced by Tobacco Smoking during Rest and Exercise Is Not Associated with Nicotine.

Lactate is a metabolite produced during anaerobic glycolysis for ATP resynthesis, which accumulates during hypoxia and muscle contraction. Tobacco smoking significantly increases blood lactate. Here we conducted a counter-balanced crossover study to examine whether this effect is associated with inhaling nicotine or burned carbon particles. Fifteen male smokers (aged 23 to 26 years) were randomized into 3 inhalation conditions: tobacco smoking, nicotine vaping, and nicotine-free vaping, conducted two days apart. An electronic thermal evaporator (e-cigarette) was used for vaping. We have observed an increased blood lactate (+62%, main effect: p < 0.01) and a decreased blood glucose (−12%, main effect: p < 0.05) during thermal air inhalations regardless of the content delivered. Exercise-induced lactate accumulation and shuttle run performance were similar for the 3 inhalation conditions. Tobacco smoking slightly increased the resting heart rate above the two vaping conditions (p < 0.05), implicating the role of burned carbon particles on sympathetic stimulation, independent of nicotine and thermal air. The exercise response in the heart rate was similar for the 3 conditions. The results of the study suggest that acute hypoxia was induced by breathing thermal air. This may explain the reciprocal increases in lactate and decreases in glucose. The impaired lung function in oxygen delivery of tobacco smoking is unrelated to nicotine.

Two weeks of detraining reduces cardiopulmonary function and muscular fitness in endurance athletes.

We investigated the effects of 2 weeks of detraining on cardiopulmonary function and muscular fitness in 15 endurance-trained male athletes (age: 19-26 years; height: 176.1 ± 7.5 cm; body mass: 68.3 ± 7.6 kg). VO2max, exercise time to exhaustion (ET), maximal stroke volume (SVmax), maximal heart rate (HRmax), isokinetic muscle strength, and muscle endurance were measured before and after 2 weeks of detraining. We determined that short-term detraining resulted in a significant decrease (p < 0.05) in VO2max, ET, SVmax and isokinetic knee extensor strength but not in isokinetic knee flexor strength or muscle endurance. HRmax and body mass increased significantly (p < 0.05), whereas body fat percentage remained stable after detraining. Furthermore, significant correlations were identified between VO2max and SVmax (p < 0.01, r = 0.6) and between VO2max and knee extensor strength (p < 0.01, r = 0.6). The results suggest that 2 weeks of detraining reduces cardiopulmonary functions, possibly as a result of the attenuation of hemodynamic and neuromuscular adaptations. Moreover, we observed that short periods of detraining appeared to increase lean mass and maintain muscle endurance in endurance runners.HighlightsTwo weeks of detraining reduces VO2max, SVmax and muscle strength but maintains muscle endurance in male runners.Short periods of detraining may enhance anabolic hormonal milieu and increase lean mass.Detraining reduced cardiopulmonary function is associated with attenuation of hemodynamic and muscle adaptations.

Effects of Running Exercise Combined With Blood Flow Restriction on Strength and Sprint Performance.

ABSTRACT: Chen, YT, Hsieh, YY, Ho, JY, and Lin, JC. Effects of running exercise combined with blood flow restriction on strength and sprint performance. J Strength Cond Res 35(11): 3090-3096, 2021-We investigated muscle strength and sprint performance after combining running exercise (RE) with blood flow restriction (BFR). Twelve male sprinters received 2 experimental warm-ups: (a) RE (50% heart rate reserve, 2 minutes × 5 sets, 1-minute rest interval) with BFR (occlusion pressure: 1.3 × resting systolic blood pressure) warm-up, namely RE-BFR; and (b) RE without BFR warm-up, namely RE. Isokinetic strength or 60-m sprint performance was assessed after a 5-minute recovery from each experimental warm-up. All subjects completed 4 exercise trials in a counterbalanced order: (a) RE-BFR-strength; (b) RE-strength; (c) RE-BFR-sprint; and (d) RE-sprint. Muscle activation (during RE), blood lactate (BLa) (pre- and post-REs), heart rate (HR), and rating of perceived exertion (RPE) (pre- and post-REs and at a 5-minute recovery) were determined during each experimental warm-up. The isokinetic knee flexor strength and the hamstring-quadriceps (H:Q) ratio observed for the RE-BFR warm-up were significantly higher than those observed for the RE warm-up (p < 0.05). However, no differences (p > 0.05) in the isokinetic knee extensor strength and 60-m sprint performance were observed between the 2 warm-ups. Running exercise-BFR warm-up induced a higher level of vastus lateralis and biceps femoris muscle activation than did RE warm-up (p < 0.05). Furthermore, RE-BFR warm-up induced higher HR, RPE, and BLa values than did RE warm-up after RE and at a 5-minute recovery (p < 0.05). These results suggest that RE-BFR warm-up may augment physiological responses and improve the H:Q ratio and isokinetic knee flexor strength. Thus, RE-BFR warm-up may be considered a practical warm-up strategy for promoting muscle strength and reducing the risk of hamstring injury in male sprinters.

Acute responses of bone specific and related markers to maximal eccentric exercise of the knee extensors and flexors in young men.

OBJECTIVES: The present study determined time-course changes in plasma bone-specific and -related markers following a bout of maximal eccentric contractions (MaxEC) of bilateral knee extensors (KE) and flexors (KF). METHODS: Sedentary young men (n=30) performed a bout of 10 sets of 10 MaxEC (30°/s) of KE and KF with each leg, respectively. Maximal voluntary isometric contraction (MVC) torque, muscle soreness (SOR), plasma creatine kinase (CK) activity, insulin, leptin, tumor necrosis factor-α (TNF-α), undercarboxylated-osteocalcin (ucOCN), carboxy-terminal crosslinking telopeptide of type I collagen (CTX-1) and procollagen type I N-terminal propeptide (P1NP) concentrations were measured from before to 7 days after MaxEC. RESULTS: Significant changes in MVC (KE: -28%, KF: -38%), SOR and plasma CK activity (peak: 39,163 IU/L) following MaxEC were evident (P<0.05) compared to baseline. Plasma leptin (17%) concentrations decreased at 1 day after MaxEC. In bone related markers, plasma ucOCN concentrations (20%) increased at 7 days after MaxEC, and plasma CTX-1 concentrations decreased at 2, 4 and 7 days after MaxEC (6~7%; P<0.05). CONCLUSION: These results demonstrate that a lean effect of bone generation and an enhanced energy anabolism can be induced by a single bout of MaxEC.

Cigarette Smoking Blunts Exercise-Induced Heart Rate Response among Young Adult Male Smokers.

This study aimed to examine the exercise-induced heart rate response (HRR) and heart rate variability (HRV) in subjects caused by inhaling smoke from tobacco cigarettes (TC) and aerosolized vapor from electronic nicotine dispensing systems (ENDS) (commonly referred to as e-cigarettes (EC)). A randomized crossover study recruited 24 young adult male smokers with an average age of 23 years and with a smoking habit of at least two years. Heart rate response was recorded after a maximal multistage shuttle 20 m run test (MMST) under three different levels of nicotine: Control 0 mg nicotine of EC (C), 3 mg nicotine of EC (3EC), and 3 mg nicotine of TC (3TC). HRV was evaluated based on the beat-to-beat time interval during the running test. The results showed no statistically significant differences in the run time to exhaustion under the three conditions (C: 398 ± 151 s; 3EC: 399 ± 160 s; 3TC: 381 ± 150 s). Exercise-induced HRR was significantly attenuated under the TC condition (p < 0.05). Intriguingly, the HRV standard deviation of normal-to-normal intervals (SDNN) during exercise significantly increased under 3EC and 3TC. The results showed that a significant acute autonomic cardiac modulation during exercise is induced by an acute episode of EC and TC smoking.

Green tea extract supplementation does not hamper endurance-training adaptation but improves antioxidant capacity in sedentary men.

The purpose of this study was to investigate the effect of green tea extract (GTE) supplementation combined with endurance training on endurance capacity and performance in sedentary men. Forty untrained men (age: 20 ± 1 years) participated in this study. Subjects were assigned to 1 of 4 treatments: (i) placebo-control (CTRL), (ii) GTE, (iii) endurance training (Ex), and (iv) endurance training with GTE (ExGTE). During the 4-week intervention, exercise training was prescribed as 75% oxygen uptake reserve for three 20-min sessions per week, and either GTE (250 mg/day) or placebo was provided. Endurance capacity, malondialdehyde (MDA), total antioxidant status (TAS), and creatine kinase (CK) were examined. Ex and ExGTE but not GTE improved exhaustive-run time (Ex: +8.2%, p = 0.031; ExGTE: +14.3%, p < 0.001); in addition, Ex and ExGTE significantly increased maximal oxygen uptake by ∼14% (p = 0.041) and ∼17% (p = 0.017) above the values of the CTRL group, respectively. Both Ex and ExGTE significantly decreased the increase of CK by ∼11%-32% below that of CTRL following an exhaustive run (Ex: p = 0.007; ExGTE: p = 0.001). Moreover, TAS levels increased by ∼11% in ExGTE after training (p = 0.040), and GTE, Ex, and ExGTE markedly attenuated exercise-induced MDA production (p = 0.01, p = 0.005, p = 0.011, respectively). In conclusion, this investigation demonstrated that daily ingestion of GTE during endurance training does not impair improvements in endurance capacity. Moreover, endurance training combined with GTE not only increases antioxidant capacity without attenuating endurance training adaptations, but also further attenuates acute exercise-induced CK release.

Immediate effects of ischemic compression on neck function in patients with cervicogenic cephalic syndrome.

OBJECTIVE: Cervicogenic cephalic syndrome (CCS), a group of diseases, consists of cervicogenic headache and dizziness. These symptoms may cause loss of physical function compared with other headache and dizziness disorders. The purpose of this case-control study was to assess the clinical effects of ischemic compression (IC) in patients with CCS. METHODS: Twenty-seven subjects with chronic neck pain (persisting for >3 months) and 26 healthy volunteers were examined. Subjects with organic lesion of the ear, nose, throat, eye, or central nervous system were excluded. The CCS group received IC over the maximal tender points of the origin of the posterior nuchal muscle. Sensory organization test (SOT) scores, cervical range of motion (ROM), and isometric strength of neck were measured before IC and after IC. RESULTS: The ROM of the cervical spine increased in all directions after IC (P < .0083) in the CCS group, and isometric strength in the CCS group rose in all directions after IC (P = .000). There was a significant difference in ankle strategy score under the sway-referenced vision and fixed support condition (P = .003) between the control group and CCS before IC. The ankle strategy score of the CCS group improved substantially after IC under eyes closed and sway-referenced support conditions (P = .003). The visual and vestibular ratios in the CCS group also increased after IC (P = .006 and P = .002, respectively). CONCLUSIONS: The findings of this study showed that ROM of the cervical spine and isometric strength increased in all directions, and the SOT scores showed increased postural stability under conditions with swayed reference support after IC in the CCS group. The ratios for vestibular and visual function also increased after IC in the CCS group.

Caffeine's effect on intermittent sprint cycling performance with different rest intervals.

The purpose of this study was to investigate the effects of caffeine ingestion on the performance of an intermittent sprint cycling test (ISCT) with different rest intervals. Fourteen males with team sport experience consumed 6 mg kg(-1) of caffeine or a placebo 60 min prior to completing two sets of an ISCT with 4-min rest intervals. Each set consisted of 12 × 4-s sprints with 20- or 90-s active recovery intervals at 60-70 rpm. Blood lactate was collected at baseline and immediately following the completion of six sprints in each set. At 20-s recovery intervals, peak power and total work were not significantly different between conditions during the ISCT (P > 0.05); but caffeine reduced 6.31% effort for mean power in Sprint 10 of the later stage, as well as an increased fatigue index and elevated blood lactate levels during the ISCT (P < 0.05). At 90-s recovery intervals, peak power, mean power, and total work under caffeine conditions were significantly higher than under placebo conditions during the ISCT (P < 0.05), but no differences were apparent in fatigue index and blood lactate levels (P > 0.05). In conclusion, caffeine ingestion may be ergolytic, affecting performance and fatigue development in the later stage during a prolonged and intermittent sprint test with a short recovery interval. However, caffeine produces an ergogenic effect in the initial stage of an intermittent sprint performance with a longer recovery interval.

Effect of caffeine ingestion after creatine supplementation on intermittent high-intensity sprint performance.

The aim of this study was to investigate the effects of acute caffeine ingestion on intermittent high-intensity sprint performance after 5 days of creatine loading. After completing a control trial (no ergogenic aids, CON), twelve physically active men were administered in a double-blind, randomized crossover protocol to receive CRE + PLA (0.3 g kg(-1) day(-1) of creatine for 5 days then followed by 6 mg kg(-1) of placebo) and CRE + CAF (0.3 g kg(-1) day(-1) of creatine for 5 days and followed by 6 mg kg(-1) of caffeine), after which they performed a repeated sprint test. Each test consisted of six 10-s intermittent high-intensity sprints on a cycling ergometer, with 60-s rest intervals between sprints. Mean power, peak power, rating of perceived exertion (RPE), and heart rates were measured during the test. Blood samples for lactate, glucose, and catecholamine concentrations were drawn at specified intervals. The mean and peak power observed in the CRE + CAF were significantly higher than those found in the CON during Sprints 1 and 3; and the CRE + CAF showed significantly higher mean and peak power than that in the CRE + PLA during Sprints 1 and 2. The mean and peak power during Sprint 3 in the CRE + PLA was significantly greater than that in the CON. Heart rates, plasma lactate, and glucose increased significantly with CRE + CAF during most sprints. No significant differences were observed in the RPE among the three trials. The present study determined that caffeine ingestion after creatine supplements augmented intermittent high-intensity sprint performance.

Functional isokinetic strength ratios in baseball players with injured elbows.

CONTEXT: Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury. OBJECTIVE: The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players. DESIGN: Retrospective study. SETTING: Biomechanics laboratory. PARTICIPANTS: College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited. INTERVENTION AND MAIN OUTCOME MEASURES: Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60 degrees and 240 degrees/s. Functional isokinetic ratios were calculated and compared between groups. RESULTS: Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status. CONCLUSIONS: These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.

Decreased anaerobic performance and hormone adaptation after expedition to Peak Lenin.

BACKGROUND: The change of anaerobic exercise abilities during and after a high-altitude expedition or hypoxic exposure is not well studied. To evaluate the effects of an extreme-altitude expedition on anaerobic performance, the 10-second supramaximal test and endocrine hormones were evaluated before and after an expedition to Peak Lenin. METHODS: Four subjects (3 male and 1 female, age (30.5 +/- 16.5) years) were recruited into the study. Three sets of tests were performed, including a basic test at sea level and 20 days before first arrival at the base camp (3600 m), a middle test done at day after returning from the summit to the base camp and the post test at the 10th day after return to the sea level. Both the supramaximal test, performed by a cycle ergometer, and body composition, performed by bioelectrical impedance analysis, were completed before the basic test and post test. The endocrine hormones including cortisol, growth hormone, testosterone, noradrenaline, adrenaline, dopamine, glucagon and beta-endorphin were measured at all tests. RESULTS: Comparing the conditions before and after the expedition, the body measurement parameters were decreased after the expedition, i.e., body weight (-4.22%, P < 0.05), fat-free mass (-2.09%, P < 0.01) and body fat (-8.95%, P = 0.172). The peak power relative/body weight ratio (PP/BW) was similar ((9.70 +/- 1.97) vs (9.11 +/- 1.80) W/kg, P = 0.093), while mean power/body weight ratio (MP/BW) was reduced significantly after the expedition ((9.14 +/- 1.77) vs (8.33 +/- 1.74) W/kg, P < 0.05). Peak power/fat-free mass (PP/FFM), mean power/fat-free mass (MP/FFM) and fatigue index (FI) were significantly lower after the expedition (PP/FFM: (11.95 +/- 1.71) vs (10.99 +/- 1.59) W/kg, P < 0.05; MP/FFM: (11.26 +/- 1.50) vs (10.04 +/- 1.55) W/kg, P < 0.005; FI (85.55 +/- 4.17)% vs (77.25 +/- 4.40)%, P < 0.05). Hormone assays showed a significant increase of noradrenaline (basic vs middle, P < 0.05) as well as decrease of adrenaline (P < 0.05). Meanwhile, a trend towards an increase in dopamine (basic vs middle) and a decrease of beta-endorphin (basic vs post) were also noted. CONCLUSIONS: These results suggested that an expedition to an extreme altitude may have negative effects on anaerobic performance. It showed that a significant increase of noradrenaline (basic vs middle) as well as decrease of adrenaline after the expedition to Peak Lenin had occurred. The real physiological significance needs to be further investigated.