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  1. The utility of immature reticulocyte fraction as an indicator of erythropoietic response to altitude training in elite cyclists
    Nadarajan VS, Ooi CH, Sthaneshwar P, Thompson MW
    Int J Lab Hematol, 2010 Feb;32(1 Pt 2):82-7.
    PMID: 19170774 DOI: 10.1111/j.1751-553X.2008.01132.x
    Altitude training is sometimes employed by elite endurance athletes to improve their sea level performance. This improvement results from the increased red cell mass consequent upon the boost in erythropoietin (EPO) level that occurs as a response to the relatively hypoxic environment at high altitudes. We measured serum EPO levels together with various red cell and reticulocyte parameters including immature reticulocyte fraction (IRF) in eight national track-endurance cyclists, resident at sea-level, prior to and upon return from an altitude of approximately 1905 m. Reticulocytes and soluble transferrin receptor (sTfR) were significantly increased with reduction in ferritin levels immediately on return from high altitude indicating increased erythropoietic activity. IRF in particular showed a significant peak immediately on return but decline to sub-baseline levels by day 9, and recovery to baseline by day 16. Our results indicate that IRF is a sensitive marker of erythropoietic status in athletes undergoing altitude training and subsequent loss of EPO stimuli on return to sea level.
    Matched MeSH terms: Physical Endurance/physiology*
  2. Physical and physiological profiles of Malaysian dragon boat rowers
    Singh R, Singh HJ, Sirisinghe RG
    Br J Sports Med, 1995 Mar;29(1):13-5.
    PMID: 7788209
    Maximal oxygen consumption (VO2max) and maximal workload attained (WLmax) were determined in 28 Malaysian dragon boat rowers who were exercised to exhaustion on an arm ergometer. Mean VO2max was 2.75 l min-1 at a mean WLmax of 195.5 W. Anaerobic endurance power of the arms, determined by cranking at 100 RPM at a workload of 400 W and the time taken to maintain the cadence until it fell to 75 RPM, was 34.9(+/- 2.3) s. Leg performance, as determined by standing long jump and vertical jump, was 140.0(+/- 4.5) kg m and 100.3(+/- 3.1) kg m s-1 respectively. Right hand grip strength was significantly (p < 0.001) greater than the left hand. Percentage body fat of the rowers was 11.8(+/- 0.6)%. These values represent the first measurements of their kind performed on dragon boat rowers in Malaysia.
    Matched MeSH terms: Physical Endurance/physiology
  3. Carbohydrate mouth rinse is no more effective than placebo on running endurance of dehydrated and heat acclimated athletes
    Kamaruddin HK, Farah NMF, Aziz AR, Mündel T, Che Muhamed AM
    Eur J Appl Physiol, 2023 Jul;123(7):1507-1518.
    PMID: 36920510 DOI: 10.1007/s00421-023-05170-y
    PURPOSE: To determine whether carbohydrate mouth rinsing would improve endurance running performance of tropical natives in a warm-humid (30 °C and 70% relative humidity) environment.

    METHOD: Twelve endurance male runners [age 25 ± 3 years; peak aerobic capacity ([Formula: see text]O2peak) 57.6 ± 3.6 mL.kg-1.min-1] completed three time-to-exhaustion (TTE) trials at ~ 70% [Formula: see text]O2peak while swilling 25 ml of a 6% carbohydrate (CHO) or taste-matched placebo (PLA) as well as no mouth rinse performed in the control (CON) trial.

    RESULTS: TTE performance was significantly longer in both CHO and PLA trials when compared with the CON trial (54.7 ± 5.4 and 53.6 ± 5.1 vs. 48.4 ± 3.6 min, respectively; p  0.05). Similarly, plasma lactate and glucose as well as exercise heart rate were not influenced by the trials.

    CONCLUSIONS: The present study demonstrates that mouth rinsing, whether carbohydrate or placebo, provides an ergogenic benefit to running endurance when compared to CON in a heat stress environment. Nevertheless, the results do not support the notion that rinsing a carbohydrate solution provides a greater advantage as previously described among non-heat acclimated individuals within a temperate condition.

    Matched MeSH terms: Physical Endurance/physiology
  4. Fulltext Cardiorespiratory parameters before and after acupuncture: observations in a healthy and diseased state
    Mohan V, Das S
    Clinics (Sao Paulo), 2012;67(6):673-4.
    PMID: 22760909
    Comment on: Nascimento RC, Hossri CA, Berwanger O, Carvalho VO. Acupuncture and exercise capacity: a case report. Clinics. 2012;67(2):193–4
    Matched MeSH terms: Physical Endurance/physiology*
  5. Central effects of mouth rinses on endurance and strength performance
    Tan SH, Khong TK, Selvanayagam VS, Yusof A
    Eur J Appl Physiol, 2024 Feb;124(2):403-415.
    PMID: 38038740 DOI: 10.1007/s00421-023-05350-w
    Rinsing the mouth with a carbohydrate (CHO) solution has been shown to enhance exercise performance while reducing neuromuscular fatigue. This effect is thought to be mediated through the stimulation of oral receptors, which activate brain areas associated with reward, motivation, and motor control. Consequently, corticomotor responsiveness is increased, leading to sustained levels of neuromuscular activity prior to fatigue. In the context of endurance performance, the evidence regarding the central involvement of mouth rinse (MR) in performance improvement is not conclusive. Peripheral mechanisms should not be disregarded, particularly considering factors such as low exercise volume, the participant's fasting state, and the frequency of rinsing. These factors may influence central activations. On the other hand, for strength-related activities, changes in motor evoked potential (MEP) and electromyography (EMG) have been observed, indicating increased corticospinal responsiveness and neuromuscular drive during isometric and isokinetic contractions in both fresh and fatigued muscles. However, it is important to note that in many studies, MEP data were not normalised, making it difficult to exclude peripheral contributions. Voluntary activation (VA), another central measure, often exhibits a lack of changes, mainly due to its high variability, particularly in fatigued muscles. Based on the evidence, MR can attenuate neuromuscular fatigue and improve endurance and strength performance via similar underlying mechanisms. However, the evidence supporting central contribution is weak due to the lack of neurophysiological measures, inaccurate data treatment (normalisation), limited generalisation between exercise modes, methodological biases (ignoring peripheral contribution), and high measurement variability.Trial registration: PROSPERO ID: CRD42021261714.
    Matched MeSH terms: Physical Endurance/physiology
  6. Effects of blood flow restriction training on physical fitness among athletes: a systematic review and meta-analysis
    Yang K, Chee CS, Abdul Kahar J, Tengku Kamalden TF, Li R, Qian S
    Sci Rep, 2024 Jul 18;14(1):16615.
    PMID: 39025894 DOI: 10.1038/s41598-024-67181-9
    Blood flow restriction training (BFRT) is an effective, scientific and safe training method, but its effect on the overall quality of athletes remains unclear. The aim of this systematic review with meta-analysis was to clarify the effects of BFRT on the physical fitness among athletes. Based on the PRISMA guidelines, searches were performed in PubMed, Web of Science, SPORTDiscus, and SCOUPS, the Cochrane bias risk assessment tool was used to assess methodological quality, and RevMan 5.4 and STATA 15.0 software were used to analyze the data. A meta-analysis of 28 studies with a total sample size of 542 athletes aged 14-26 years and assessed as low risk for quality was performed. Our results revealed that the BFRT intervention had small to large improvements in the athletes' strength (ES = 0.74-1.03), power (ES = 0.46), speed (ES = 0.54), endurance (ES = 1.39-1.40), body composition (ES = 0.28-1.23), while there was no significant effect on body mass (p > 0.05). Subgroup analyses revealed that moderator variables (training duration, frequency, load, cuff pressure, and pressurization time) also had varying degrees of effect on athletes' physical fitness parameters. In conclusion, BFRT had a positive effect on the physical fitness parameters of the athletes, with significantly improved strength, power, speed, endurance and body composition, but not body mass parameters. When the training frequency ≥ 3 times/week, cuff pressure ≥ 160 mmHg, and pressurization time ≥ 10 min, the BFRT group was more favorable for the improvement of physical fitness parameters.
    Matched MeSH terms: Physical Endurance/physiology
  7. Enhancing Physical Fitness in Elite Field Hockey Players with A Twelve-Week Functional Training Program: A Cluster Randomized Control Trial
    Bashir M, Hucheng M, Geok SK, Akbar S, Zhang D
    J Sports Sci Med, 2024 Sep;23(1):628-637.
    PMID: 39228773 DOI: 10.52082/jssm.2024.628
    This study aimed to explore the impact of functional training on the physical fitness of young elite field hockey players. The study comprised 40 young elite male field hockey players with the following characteristics (mean ± SD age: 21.5 ± 0.8 years; height: 176.9 ± 2.6 cm; weight: 68.4 ± 5.1 kg; BMI: 21.8 ± 1.3; training experience: 51.2 ± 5.4 months). Twenty participants were allocated to two groups: the functional training group (FTG) and the control training group (CG). Each group received 60-minute training sessions three times per week for 12 weeks. Generalized estimating equation analysis and a Bonferroni test for pairwise comparisons were used to assess the intervention's efficacy. Before the start of the exercise program, no statistically significant differences were observed in physical fitness measures between the FTG and CG (p > 0.05). However, by the sixth week, a significant difference appeared in both the T-Agility test (p < 0.001) and endurance (p = 0.024) between the two groups, while no notable distinctions were detected in other fitness parameters (p > 0.05). After a 12-week training program, the FTG demonstrated improvements in all physical fitness measures [flexibility (p < 0.001); Illinois agility test (p < 0.001); T-agility test (p = 0.020); endurance (p < 0.001)] except speed, which exhibited no significant impact (p = 0.175). Notable enhancements in T-agility and endurance were evident after just six weeks of functional training, and a 12-week functional training regimen showed superiority over standard training approaches in young elite male field hockey players. These findings encourage the efficacy of functional training exercises over traditional methods in enhancing athletes' fitness parameters.
    Matched MeSH terms: Physical Endurance/physiology
  8. Mouth rinsing improves cycling endurance performance during Ramadan fasting in a hot humid environment
    Che Muhamed AM, Mohamed NG, Ismail N, Aziz AR, Singh R
    Appl Physiol Nutr Metab, 2014 Apr;39(4):458-64.
    PMID: 24669987 DOI: 10.1139/apnm-2013-0276
    This study examined the effect of mouth rinsing during endurance cycling in a hot humid environment (32 °C and 75% relative humidity) on athletes in the Ramadan fasted state. Nine trained adolescent male cyclists completed 3 trials that consisted of a carbohydrate mouth-rinse (CMR), a placebo mouth-rinse (PMR), and a no-rinse (NOR) trial during the last 2 weeks of Ramadan. Each trial consisted of a preloading cycle at 65% peak rate of oxygen consumption for 30 min followed by a 10-km time trial (TT10 km) under hot humid condition. During the CMR and PMR trials, each cyclist rinsed his mouth with 25 mL of the solution for 5 s before expectorating the solution pre-exercise, after 5, 15, and 25 min of the preloading cycle, and 15 s prior to the start of TT10 km. Time to complete the TT10 km was significantly faster in the CMR and PMR trials compared with the NOR trial (12.9 ± 1.7 and 12.6 ± 1.7 vs. 16.8 ± 1.6 min, respectively; p < 0.017). Ratings of perceived exertion taken at the end of the TT10 km was lower in both CMR and PMR trials compared with the NOR trial, although the difference was significant only between CMR and NOR (p < 0.05). In conclusion, mouth rinsing with either carbohydrate or placebo solution provided ergogenic benefits compared with a no-rinse condition on TT10 km performance in acute Ramadan fasted subjects during endurance cycling in a heat stress environment.
    Matched MeSH terms: Physical Endurance/physiology*
  9. Fulltext Fatigue index and fatigue rate during an anaerobic performance under hypohydrations
    Naharudin MN, Yusof A
    PLoS One, 2013;8(10):e77290.
    PMID: 24204790 DOI: 10.1371/journal.pone.0077290
    BACKGROUND: Since hypohydration commonly occurs in sports, studies on anaerobic exercise performance under this condition have been extensively carried out. When describing anaerobic performance, authors usually refer to a drop in anaerobic performance as fatigue index (FI) which is conventionally calculated using peak and low power data points. Meanwhile, another possible method in explaining anaerobic fatigue is using the rate constant which is derived from the exponential decline of power output known as fatigue rate (FR). Few studies have demonstrated that there was no change in anaerobic performance under mild hypohydrations.

    PURPOSE: This study aimed to compare the kinetics of power output using FI and FR of an anaerobic performance (Wingate test) under 2, 3 and 4% state of hypohydrations.

    METHOD: Thirty two collegiate cyclists (age = 22 ± 2 years; body weight = 71.45 ± 3.43 kg; height = 173.23 ± 0.04 cm) were matched using their baseline anaerobic peak power (APP) then randomly divided into 4 groups of EU (euhydrated), 2H, 3H and 4H respectively.

    RESULTS: As expected the, FI, APP, anaerobic lower power (ALP) and rating of perceived exertion (RPE) did not show significant differences between and within the groups. However, the FR in 3H (0.018 ± 0.005 s(-1)) and 4H (0.019 ± 0.010 s(-1)) were significantly lower than EU (0.033 ± 0.012 s(-1)). Post-test FR also showed significant reduction in 3H and 4H compared to their pre-test values (p<0.05).

    CONCLUSION: Despite the lack of changes in APP and RPE, subjects in 3H and 4H showed evidence of lower reduction of power output over time. The findings support earlier reports which showed no change in anaerobic performance under mild hypohydrations. The relatively lower FR suggests higher drive in maintaining power output under hypohydrations of 3 and 4% body weight.

    Matched MeSH terms: Physical Endurance/physiology*
  10. Anaerobic capacity of physically active eumenorrheic females at mid-luteal and mid-follicular phases of ovarian cycle
    Shaharudin S, Ghosh AK, Ismail AA
    J Sports Med Phys Fitness, 2011 Dec;51(4):576-82.
    PMID: 22212259
    The present study was undertaken to evaluate the anaerobic capacity in repeated sprint cycling bouts during mid-luteal (ML) and mid-follicular (MF) phases of ovarian cycle.
    Matched MeSH terms: Physical Endurance/physiology*
  11. Non-uniform decay in jumping exercise-induced bone gains following 12 and 24 weeks of cessation of exercise in rats
    Ooi FK, Singh R, Singh HJ, Umemura Y, Nagasawa S
    J Physiol Sci, 2011 Nov;61(6):487-95.
    PMID: 21870136 DOI: 10.1007/s12576-011-0169-4
    The effects of deconditioning on exercise-induced bone gains in rats were investigated in 12-week-old female WKY rats performing a standard jumping exercise regimen for either 8, 12 or 24 weeks, followed by sedentary periods of either 24, 12 or 0 weeks, respectively. Age-matched controls received no exercise over the same period. At the end of the training/sedentary period, the tibiae were harvested for analyses of bone parameters. Gains in tibial fat-free dry weight decayed within 12 weeks of deconditioning, but gains in tibial ultimate bending force (strength), maximum diameter and cortical area were still present at 12 weeks of deconditioning. With the exception of cortical area, all other exercise-induced bone gains decayed by the 24th week of deconditioning. It appears that the decay in exercise-induced bone gains in strength, physical and morphological properties is not uniform, and that gains in fat-free dry weight seem to decay earlier.
    Matched MeSH terms: Physical Endurance/physiology*
  12. Leisure-time physical activity and physical fitness of male adolescents in Oman
    Khoo S, Al-Shamli AK
    Asia Pac J Public Health, 2012 Jan;24(1):128-35.
    PMID: 20460285 DOI: 10.1177/1010539510366178
    This study investigated the relationship between leisure-time physical activity and physical fitness (cardiovascular fitness, body fat percentage, flexibility, muscle strength, and endurance) of 10th-grade male students in Oman. Data were collected from 330 students. All participants completed a descriptive questionnaire, a 1 mile walk/run test; a skinfold analysis of the chest, abdomen, and thigh; a sit and reach test; a hand grip test; and a 1-minute sit-up test. Students spent an average of 19.20 ± 6.77 hours on sedentary activities, 3.46 ± 2.11 hours on sports activities, and 11.22 ± 9.24 hours working per week. The students had an average body fat percentage of 6.38% ± 4.67%, muscle strength 38.04 ± 7.55 kg, flexibility 38.01 ± 7.41 cm, abdominal muscle endurance 38.85 ± 8.15 times/min, and cardiovascular endurance 8.10 ± 1.65 minutes.
    Matched MeSH terms: Physical Endurance/physiology
  13. Effect of acute exercise on the levels of salivary cortisol, tumor necrosis factor-alpha and nitric oxide
    Rahman ZA, Abdullah N, Singh R, Sosroseno W
    J Oral Sci, 2010 Mar;52(1):133-6.
    PMID: 20339244
    The aim of the present study was to assess the levels of salivary cortisol, tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) before, during and after acute exercise. Acute exercise was induced using a standard treadmill test with Bruce protocol in ten physically active male participants. Unstimulated saliva was collected before, during and after exercise. The levels of salivary cortisol and TNF-alpha were assessed by enzyme immunoassays. Salivary NO was determined by the Griess reagent. The results showed that both salivary cortisol and TNF-alpha increased and peaked at 14 min during exercise and then decreased. The levels of NO were increased up to 1 h after exercise and subsequently lowered after 24 h. The results of the present study suggest that acute exercise may induce high levels of salivary cortisol, TNF-alpha and NO.
    Matched MeSH terms: Physical Endurance/physiology
  14. Effects of endurance and high intensity training on ICAM-1 and VCAM-1 levels and arterial pressure in obese and normal weight adolescents
    Kargarfard M, Lam ET, Shariat A, Asle Mohammadi M, Afrasiabi S, Shaw I, et al.
    Phys Sportsmed, 2016 09;44(3):208-16.
    PMID: 27291761 DOI: 10.1080/00913847.2016.1200442
    OBJECTIVES: Obesity prevalence has increased in Iranian adolescents in recent years. However, few studies have examined the impact of intervention programs on this health issue. The main objective of this study was to evaluate the effects of 8-week endurance training (ET) and high intensity interval training (HIIT) on intercellular adhesion molecule-1(ICAM-1) and vascular adhesion molecule-1(VCAM-1) levels among obese and normal-weight male adolescents.
    METHODS: Thirty obese and 30 normal-weight subjects were assigned to the ET, HIIT, or control group for eight weeks. Before and after the intervention, ICAM-1, VCAM-1, body weight, BMI, VO2max, and blood pressures were measured. SPSS (Version 21) was used for data analysis, and the significance level was set at p 
    Matched MeSH terms: Physical Endurance/physiology*
  15. The effects of modified exponential tapering technique on perceived exertion, heart rate, time trial performance, VO2max and power output among highly trained junior cyclists
    Ishak A, Hashim HA, Krasilshchikov O
    J Sports Med Phys Fitness, 2016 Sep;56(9):961-7.
    PMID: 26004044
    BACKGROUND: The present study investigated the effects of a 2-week modified exponential taper on physiological adaptation and time trial performance among junior cyclists.

    METHODS: Participants (N.=27) with the mean age of 16.95±0.8 years, height of 165.6±6.1 cm and weight of 54.19±8.1 kg were matched into either modified exponential taper (N.=7), normal exponential taper (N.=7), or control (N.=7) groups using their initial VO2max values. Both experimental groups followed a 12-week progressive endurance training program and subsequently, a 2-week tapering phase. A simulated 20-km time trial performance along with VO2max, power output, heart rate and rating of perceived exertion were measured at baseline, pre and post-taper. One way ANOVA was used to analyze the difference between groups before the start of the intervention while mixed factorial ANOVA was used to analyze the difference between groups across measurement sessions. When homogeneity assumption was violated, the Greenhouse-Geisser Value was used for the corrected values of the degrees of freedom for the within subject factor the analysis.

    RESULTS: Significant interactions between experimental groups and testing sessions were found in VO2max (F=6.67, df=4, P<0.05), power output (F=5.02, df=4, P<0.05), heart rate (F=10.87, df=2.51, P<0.05) rating of perceived exertion (F=13.04, df=4, P<0.05) and 20KM time trial (F=4.64, df=2.63, P<0.05). Post-hoc analysis revealed that both types of taper exhibited positive effects compared to the non-taper condition in the measured performance markers at post-taper while no different were found between the two taper groups.

    CONCLUSIONS: It was concluded that both taper protocols successfully inducing physiological adaptations among the junior cyclists by reducing the volume and maintaining the intensity of training.

    Matched MeSH terms: Physical Endurance/physiology
  16. Combination of sago and soy-protein supplementation during endurance cycling exercise and subsequent high-intensity endurance capacity
    Ghosh AK, Rahaman AA, Singh R
    Int J Sport Nutr Exerc Metab, 2010 Jun;20(3):216-23.
    PMID: 20601739
    The purpose of the study was to investigate whether a combination of sago and soy protein ingested during moderate-intensity cycling exercise can improve subsequent high-intensity endurance capacity compared with a carbohydrate in the form of sago and with a placebo. The participants were 8 male recreational cyclists with age, weight, and VO2max of 21.5 +/- 1.1 yr, 63.3 +/- 2.4 kg, and 39.9 +/- 1.1 ml . kg(-1) . min(-1), respectively. The design of the study was a randomized, double-blind placebo-controlled crossover comprising 60 min of exercise on a cycle ergometer at 60% VO2max followed by a time-to-exhaustion ride at 90% VO2max. The sago feeding provided 60 g of carbohydrate, and the sago-soy combination provided 52.5 g of carbohydrate and 15 g of protein, both at 20-min intervals during exercise. Times to exhaustion for the placebo, sago, and sago-soy supplementations were 4.09 +/- 1.28, 5.49 +/- 1.20, and 7.53 +/- 2.02 min, respectively. Sago-soy supplementation increased endurance by 84% (44-140%; p < .001) and by 37% (15-63%; p < .05) relative to placebo and sago, respectively. The plasma insulin response was elevated above that with placebo during sago and sago-soy supplementations. The authors conclude that a combination of sago and soy protein can delay fatigue during high-intensity cycling.
    Matched MeSH terms: Physical Endurance/physiology
  17. Effects of sleeping with reduced carbohydrate availability on acute training responses
    Lane SC, Camera DM, Lassiter DG, Areta JL, Bird SR, Yeo WK, et al.
    J Appl Physiol (1985), 2015 Sep 15;119(6):643-55.
    PMID: 26112242 DOI: 10.1152/japplphysiol.00857.2014
    We determined the effects of "periodized nutrition" on skeletal muscle and whole body responses to a bout of prolonged exercise the following morning. Seven cyclists completed two trials receiving isoenergetic diets differing in the timing of ingestion: they consumed either 8 g/kg body mass (BM) of carbohydrate (CHO) before undertaking an evening session of high-intensity training (HIT) and slept without eating (FASTED), or consumed 4 g/kg BM of CHO before HIT, then 4 g/kg BM of CHO before sleeping (FED). The next morning subjects completed 2 h of cycling (120SS) while overnight fasted. Muscle biopsies were taken on day 1 (D1) before and 2 h after HIT and on day 2 (D2) pre-, post-, and 4 h after 120SS. Muscle [glycogen] was higher in FED at all times post-HIT (P < 0.001). The cycling bouts increased PGC1α mRNA and PDK4 mRNA (P < 0.01) in both trials, with PDK4 mRNA being elevated to a greater extent in FASTED (P < 0.05). Resting phosphorylation of AMPK(Thr172), p38MAPK(Thr180/Tyr182), and p-ACC(Ser79) (D2) was greater in FASTED (P < 0.05). Fat oxidation during 120SS was higher in FASTED (P = 0.01), coinciding with increases in ACC(Ser79) and CPT1 as well as mRNA expression of CD36 and FABP3 (P < 0.05). Methylation on the gene promoter for COX4I1 and FABP3 increased 4 h after 120SS in both trials, whereas methylation of the PPARδ promoter increased only in FASTED. We provide evidence for shifts in DNA methylation that correspond with inverse changes in transcription for metabolically adaptive genes, although delaying postexercise feeding failed to augment markers of mitochondrial biogenesis.
    Matched MeSH terms: Physical Endurance/physiology*
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