• Are there limits to running world records?

      Nevill, Alan M.; Whyte, Gregory P. (American College of Sports Medicine, 2005)
      Purpose: Previous researchers have adopted linear models to predict athletic running world records, based on records recorded throughout the 20th century. These linear models imply that there is no limit to human performance and that, based on projected estimates, women will eventually run faster than men. The purpose of this article is to assess whether a more biologically sound, flattened "S-shaped" curve could provide a better and more interpretable fit to the data, suggesting that running world records could reach their asymptotic limits some time in the future. Methods: Middle- and long-distance running world record speeds recorded during the 20th century were modeled using a flattened S-shaped logistic curve. Results: The logistic curves produce significantly better fits to these world records than linear models (assessed by separating/partitioning the explained variance from the logistic and linear models using ANOVA). The models identify a slow rise in world-record speeds during the early year of the century, followed by a period of “acceleration” in the middle of the century (due to the professionalization of sport and advances in technology and science), and a subsequent reduction in the prevalence of record-breaking performances towards the end of the century. The model predicts that men’s world records are nearing their asymptotic limits (within 1–3%). Indeed, the current women’s 1500-m world record speed of 6.51 m s 1 may well have reached its limit (time 3:50.46). Conclusions: Many of the established men’s and women’s endurance running world records are nearing their limits and, consequently, women’s world records are unlikely to ever reach those achieved by men.
    • Comparison between G6PD-Deficient and Normal Individuals after Eccentric Exercise

      Theodorou, Anastasios A.; Nikolaidis, Michalis G.; Paschalis, Vassilis; Sakellariou, Georgios K.; Fatouros, Ioannis G.; Koutedakis, Yiannis; Jamurtas, Athanasios Z. (American College of Sports Medicine, 2010)
      Purpose: Theoretically, glucose-6-phosphate dehydrogenase (G6PD)-deficient compared with nondeficient individuals may be less capable of performing physical activities and/or may be more vulnerable to muscle damage and oxidative stress. Therefore, the purpose of the present study was to examine the effects of a resistance muscle-damaging exercise bout on muscle function and damage, redox status in plasma, and erythrocytes and hemolysis. Methods: Nine males with established G6PD deficiency and nine males with normal G6PD activity performed an eccentric muscledamaging exercise protocol. Isometric torque, range of motion, delayed onset muscle soreness, and creatine kinase were measured as indices of muscle function and damage. Reduced glutathione, oxidized glutathione, thiobarbituric acid–reactive substances, protein carbonyls, catalase, uric acid, and total antioxidant capacity were measured as indices of blood redox status. Plasma hemoglobin and bilirubin were measured as indices of hemolysis. All measurements conducted before, immediately after, and 1, 2, 3, 4, and 5 d after exercise. Results: All indices measured confirmed that eccentric exercise induced severe muscle damage, oxidative stress, and hemolysis, peaking at 2 and 3 d postexercise. Lower resting levels of reduced glutathione were detected in the G6PD-deficient group compared with the control group. Nevertheless, both the time course and the magnitude of the changes of the selected muscle performance, redox status (both in plasma and in erythrocytes), and hemolysis indices measured were similar between the two groups. Conclusions: The present study indicates that G6PD-deficient individuals may participate in high-intensity muscle-damaging activities, without a negative impact on muscle function, blood redox status, and hemolysis
    • The dangers of estimating V˙O2max using linear, nonexercise prediction models

      Nevill, Alan M.; Cooke, Carlton B (American College of Sports Medicine, 2016-12-01)
      Purpose This study aimed to compare the accuracy and goodness of fit of two competing models (linear vs allometric) when estimating V˙O2max (mL·kg−1·min−1) using nonexercise prediction models. Methods The two competing models were fitted to the V˙O2max (mL·kg−1·min−1) data taken from two previously published studies. Study 1 (the Allied Dunbar National Fitness Survey) recruited 1732 randomly selected healthy participants, 16 yr and older, from 30 English parliamentary constituencies. Estimates of V˙O2max were obtained using a progressive incremental test on a motorized treadmill. In study 2, maximal oxygen uptake was measured directly during a fatigue limited treadmill test in older men (n = 152) and women (n = 146) 55 to 86 yr old. Results In both studies, the quality of fit associated with estimating V˙O2max (mL·kg−1·min−1) was superior using allometric rather than linear (additive) models based on all criteria (R2, maximum log-likelihood, and Akaike information criteria). Results suggest that linear models will systematically overestimate V˙O2max for participants in their 20s and underestimate V˙O2max for participants in their 60s and older. The residuals saved from the linear models were neither normally distributed nor independent of the predicted values nor age. This will probably explain the absence of a key quadratic age2 term in the linear models, crucially identified using allometric models. Not only does the curvilinear age decline within an exponential function follow a more realistic age decline (the right-hand side of a bell-shaped curve), but the allometric models identified either a stature-to-body mass ratio (study 1) or a fat-free mass-to-body mass ratio (study 2), both associated with leanness when estimating V˙O2max. Conclusions Adopting allometric models will provide more accurate predictions of V˙O2max (mL·kg−1·min−1) using plausible, biologically sound, and interpretable models.
    • Determinants of 800-m and 1500-m Running Performance Using Allometric Models

      Ingham, Stephen A.; Whyte, Gregory P.; Pedlar, Charles R.; Bailey, David M.; Dunman, Natalie; Nevill, Alan M. (American College of Sports Medicine, 2008)
      Purpose: To identify the optimal aerobic determinants of elite, middle-distance running (MDR) performance, using proportional allometric models. Methods: Sixty-two national and international male and female 800-m and 1500-m runners undertook an incremental exercise test to volitional exhaustion. Mean submaximal running economy (ECON), speed at lactate threshold (speedLT), maximum oxygen uptake (V˙ O2max), and speed associated with V˙ O2max (speedV˙ O2max) were paired with best performance times recorded within 30 d. The data were analyzed using a proportional power-function ANCOVA model. Results: The analysis identified significant differences in running speeds with main effects for sex and distance, with V˙ O2max and ECON as the covariate predictors (P G 0.0001). The results suggest a proportional curvilinear association between running speed and the ratio (V˙ O2maxIECONj0.71)0.35 explaining 95.9% of the variance in performance. The model was cross-validated with a further group of highly trained MDR, demonstrating strong agreement (95% limits, 0.05 T 0.29 mIsj1) between predicted and actual performance speeds (R 2 = 93.6%). The model indicates that for a male 1500-m runner with a V˙ O2max of 3.81 LIminj1 and ECON of 15 LIkmj1 to improve from 250 to 240 s, it would require a change in V˙ O2max from 3.81 to 4.28 LIminj1, an increase of $0.47 LIminj1. However, improving by the same margin of 10 s from 225 to 215 s would require a much greater increase in V˙ O2max, from 5.14 to 5.85 LIminj1 an increase of $0.71 LIminj1 (where ECON remains constant). Conclusion: A proportional curvilinear ratio of V˙ O2max divided by ECON explains 95.9% of the variance in MDR performance.
    • Ergogenic and Antioxidant Effects of Spirulina Supplementation in Humans

      Kalafati, Maria; Jamurtas, Athanasios Z.; Nikolaidis, Michalis G.; Paschalis, Vassilis; Theodorou, Anastasios A.; Sakellariou, G. K.; Koutedakis, Yiannis; Kouretas, Dimitris (American College of Sports Medicine, 2010)
      Purpose: Spirulina is a popular nutritional supplement that is accompanied by claiMSS for antioxidant and performance-enhancing effects. Therefore, the aim of the present study was to examine the effect of spirulina supplementation on (i) exercise performance, (ii) substrate metabolism, and (iii) blood redox status both at rest and after exercise. Methods: Nine moderately trained males took part in a double-blind, placebo-controlled, counterbalanced crossover study. Each subject received either spirulina (6 gd-1) or placebo for 4 wk. Each subject ran on a treadmill at an intensity corresponding to 70%–75% of their VO2max for 2 h and then at 95% VO2max to exhaustion. Exercise performance and respiratory quotient during exercise were measured after both placebo and spirulina supplementation. Blood samples were drawn before, immediately after, and at 1, 24, and 48 h after exercise. Reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG, thiobarbituric acid-reactive substances (TBARS), protein carbonyls, catalase activity, and total antioxidant capacity (TAC) were determined. Results: Time to fatigue after the 2-h run was significantly longer after spirulina supplementation (2.05 ± 0.68 vs 2.70 ± 0.79 min). Ingestion of spirulina significantly decreased carbohydrate oxidation rate by 10.3% and increased fat oxidation rate by 10.9% during the 2-h run compared with the placebo trial. GSH levels were higher after the spirulina supplementation compared with placebo at rest and 24 h after exercise. TBARS levels increased after exercise after placebo but not after spirulina supplementation. Protein carbonyls, catalase, and TAC levels increased similarly immediately after and 1 h after exercise in both groups. Conclusions: Spirulina supplementation induced a significant increase in exercise performance, fat oxidation, and GSH concentration and attenuated the exercise-induced increase in lipid peroxidation.
    • Maximal voluntary quadriceps strength patterns in Olympic overtrained athletes.

      Koutedakis, Yiannis; Frischknecht, R.; Vrbová, G.; Sharp, N. C. Craig; Budgett, Richard; School of Health Sciences, Wolverhampton University, Wolverhampton, England. (American College of Sports Medicine, 1995)
      Peak torques were studied in 10 elite male overtrained athletes and 10 controls matched for sex, age, sport, and performance level. Isokinetic concentric (CON) and eccentric (ECC) maximal voluntary contractions (MVC) of quadriceps muscle were assessed at the angular velocities of 60 degrees, 120 degrees, and 180 degrees.s-1. Sustained isometric MVCs were also measured at knee angles of 10 degrees, 45 degrees, and 80 degrees of flexion. Six seconds after the beginning of each isometric MVC, a 40-Hz electrical stimulation was superimposed on the MVC for a further 6 s. The overtrained subjects developed significantly smaller CON peak torques at 180 degrees.s-1 (P < 0.001), although ECC torques were similar at all three velocities. ECC/CON ratios were higher in the overtrained subjects at 120 degrees.s-1 (P < 0.01) and 180 degrees.s-1 (P < 0.001) compared with the controls. Isometric MVCs at 10 degrees and 45 degrees knee flexion were lower in the overtrained at P < 0.01 and P < 0.05, respectively. Also in the overtrained subjects, at knee angle of 10 degrees, the addition of the electrical stimulation to the isometric MVC produced an increase (P < 0.05) in torque levels. It is suggested that impaired central drive may account for the present findings.
    • Modeling maximum oxygen uptake of elite endurance athletes

      Nevill, Alan M.; Brown, Damon; Godfrey, R.J.; Johnson, Patrick J.; Romer, Lee; Stewart, Arthur D.; Winter, Edward M. (American College of Sports Medicine, 2003)
      To compare the maximum oxygen uptake (V˙ O2max) of elite endurance athletes and to explain why the body mass exponent, necessary to render V˙ O2max independent of body mass, appears to be greater than 0.67. Methods: Study 1: V˙ O2max of 174 international sportsmen and women was assessed. Athletes were recruited from seven sports (middle- and long-distance runners, heavyweight and lightweight rowers, triathletes, and squash and badminton players). Study 2: calf and thigh leg muscle masses were estimated in 106 male and 30 female athletes from 11 sports. Differences in V˙ O2max and leg muscle masses between “sports” and “sex” were analyzed independent of body mass by using allometric log-linear ANCOVA. Results: Heavyweight rowers had the greatest V˙ O2max when expressed in L·min 1 but long-distance runners had the highest V˙ O2max in mL·kg 1·min 1. However, the ANCOVA identified no difference in “mass independent”V˙ O2max between the five “pure” endurance sports (runners, rowers, and triathletes) (P 0.05) with the two racket sports being significantly lower. The body mass covariate exponent was inflated, estimated as 0.94. The results from study 2 estimated calf and thigh leg muscle masses to increase in proportion to body mass, m1.11 and m1.38, respectively. Conclusions: After having controlled for differences in body mass,V˙ O2max did not differ between pure endurance sports (P 0.05). Assuming that athletes’ thigh muscle mass increases in proportion to body mass m1.38 as observed in study 2, a similar disproportional increase in V˙ O2max would be anticipated, providing a plausible explanation for the inflated mass exponent associated with V˙ O2max identified in this and other studies
    • Optimal Body Size and Limb Length Ratios Associated with 100-m Personal-Best Swim Speeds.

      Nevill, Alan M.; Oxford, Samuel W; Duncan, Michael J (American College of Sports Medicine, 2015-08)
      This study aims to identify optimal body size and limb segment length ratios associated with 100-m personal-best (PB) swim speeds in children and adolescents.
    • Specific respiratory warm-up improves rowing performance and exertional dyspnea

      Volianitis, Stefanos; McConnell, Alison K.; Koutedakis, Yiannis; Jones, David A. (American College of Sports Medicine, 2001)
      Purpose: The purpose of this study was a) to compare the effect of three different warm-up protocols upon rowing performance and perception of dyspnea, and b) to identify the functional significance of a respiratory warm-up. Methods: A group of well-trained club rowers (N = 14) performed a 6-min all-out rowing simulation (Concept II). We examined differences in mean power output and dyspnea measures (modified CR-Borg scale) under three different conditions: after a submaximal rowing warm-up (SWU), a specific rowing warm-up (RWU), and a specific rowing warm-up with the addition of a respiratory warm-up (RWUplus) protocol. Results: Mean power output during the 6-min all-out rowing effort increased by 1.2% after the RWUplus compared with that obtained after the RWU (P < 0.05) which, in turn, was by 3.2% higher than the performance after the SWU (P < 0.01). Similarly, after the RWUplus, dyspnea was 0.6 ± 0.1 (P < 0.05) units of the Borg scale lower compared with the dyspnea after the RWU and 0.8 ± 0.2 (P < 0.05) units lower than the dyspnea after the SWU. Conclusion: These data suggest that a combination of a respiratory warm-up protocol together with a specific rowing warm-up is more effective than a specific rowing warm-up or a submaximal warm-up alone as a preparation for rowing performance