There is growing evidence that caffeine and coffee ingestion prior to exercise provide similar ergogenic benefits. However, there has been a long-standing paradigm that habitual caffeine intake may influence the ergogenicity of caffeine supplementation. The aim of the present study was to investigate the effect of habitual caffeine intake on 5-km cycling time-trial performance following the ingestion of caffeinated coffee. Following institutional ethical approval, in a double-blind, randomized, crossover, placebo-controlled design, 46 recreationally active participants (27 men and 19 women) completed a 5-km cycling time trial on a cycle ergometer 60 m in following the ingestion of 0.09 g/kg coffee providing 3 mg/kg of caffeine, or a placebo. Habitual caffeine consumption was assessed using a caffeine consumption questionnaire with low habitual caffeine consumption defined as <3 and ≥6 mg · kg−1 · day−1 defined as high. An analysis of covariance using habitual caffeine intake as a covariant was performed to establish if habitual caffeine consumption had an impact on the ergogenic effect of coffee ingestion. Sixteen participants were classified as high-caffeine users and 30 as low. Ingesting caffeinated coffee improved 5-km cycling time-trial performance by 8 ± 12 s; 95% confidence interval (CI) [5, 13]; p < .001; d = 0.30, with low, 9±14 s; 95% CI [3, 14]; p = .002; d = 0.18, and high, 8 ± 10 s; 95% CI [−1, 17]; p = .008; d = 0.06, users improving by a similar magnitude, 95% CI [−12, 12]; p = .946; d = 0.08. In conclusion, habitual caffeine consumption did not affect the ergogenicity of coffee ingestion prior to a 5-km cycling time trial.
Neil D. Clarke and Darren L. Richardson
George P. Robinson, Sophie C. Killer, Zdravko Stoyanov, Harri Stephens, Luke Read, Lewis J. James and Stephen J. Bailey
This study investigated whether supplementation with nitrate-rich beetroot juice (BR) can improve high-intensity intermittent running performance in trained males in normoxia and different doses of normobaric hypoxia. Eight endurance-trained males (
Ali Daraei, Sajad Ahmadizad, Hiwa Rahmani, Anthony C. Hackney, Kelly E. Johnson, Ismail Laher, Ayoub Saeidi and Hassane Zouhal
The effects of acute consumption of L-Arginine (L-Arg) in healthy young individuals are not clearly defined, and no studies on the effects of L-Arg in individuals with abnormal body mass index undertaking strenuous exercise exist. Thus, we examined whether supplementation with L-Arg diminishes cardiopulmonary exercise testing responses, such as ventilation (VE), VE/VCO2, oxygen uptake (VO2), and heart rate, in response to an acute session of high-intensity interval exercise (HIIE) in overweight men. A double-blind, randomized crossover design was used to study 30 overweight men (age, 26.5 ± 2.2 years; body weight, 88.2 ± 5.3 kilogram; body mass index, 28.0 ± 1.4 kg/m2). Participants first completed a ramped-treadmill exercise protocol to determine VO2max velocity (vVO2max), after which they participated in two sessions of HIIE. Participants were randomly assigned to receive either 6 g of L-Arg or placebo supplements. The HIIE treadmill running protocol consisted of 12 trials, including exercise at 100% of vVO2max for 1 min interspersed with recovery intervals of 40% of vVO2max for 2 min. Measurements of VO2 (ml·kg−1·min−1), VE (L/min), heart rate (beat per min), and VE/VCO2 were obtained. Supplementation with L-Arg significantly decreased all cardiorespiratory responses during HIIE (placebo+HIIE vs. L-Arg+HIIE for each measurement: VE [80.9 ± 4.3 L/min vs. 74.6 ± 3.5 L/min, p < .05, ES = 1.61], VE/VCO2 [26.4 ± 1.3 vs. 24.4 ± 1.0, p < .05, ES = 1.8], VO2 [26.4 ± 0.8 ml·kg−1·min−1 vs. 24.4 ± 0.9 ml·kg−1·min−1, p < .05, ES = 2.2], and heart rate [159.7 ± 6.3 beats/min vs. 155.0 ± 3.7 beats/min, p < .05, d = 0.89]). The authors conclude consuming L-Arg before HIIE can alleviate the excessive physiological strain resulting from HIIE and help to increase exercise tolerance in participants with a higher body mass index who may need to exercise on a regular basis for extended periods to improve their health.
Naroa Etxebarria, Brad Clark, Megan L. Ross, Timothy Hui, Roland Goecke, Ben Rattray and Louise M. Burke
The ingestion of quinine, a bitter tastant, improves short-term (30 s) cycling performance, but it is unclear whether this effect can be integrated into the last effort of a longer race. The purpose of this study was to determine whether midtrial quinine ingestion improves 3,000-m cycling time-trial (TT) performance. Following three familiarization TTs, 12 well-trained male cyclists (mean ± SD: mass = 76.6 ± 9.2 kg, maximal aerobic power = 390 ± 50 W, maximal oxygen uptake = 4.7 ± 0.6 L/min) performed four experimental 3,000-m TTs on consecutive days. This double-blind, crossover design study had four randomized and counterbalanced conditions: (a) Quinine 1 (25-ml solution, 2 mM of quinine); (b) Quinine 2, replicate of Quinine 1; (c) a 25-ml sweet-tasting no-carbohydrate solution (Placebo); and (d) 25 ml of water (Control) consumed at the 1,850-m point of the TT. The participants completed a series of perceptual scales at the start and completion of all TTs, and the power output was monitored continuously throughout all trials. The power output for the last 1,000 m for all four conditions was similar: mean ± SD: Quinine 1 = 360 ± 63 W, Quinine 2 = 367 ± 63 W, Placebo = 364 ± 64 W, and Control = 367 ± 58 W. There were also no differences in the 3,000-m TT power output between conditions. The small perceptual differences between trials at specific 150-m splits were not explained by quinine intake. Ingesting 2 mM of quinine during the last stage of a 3,000-m TT did not improve cycling performance.
Christopher J. Stevens, Megan L.R. Ross and Roxanne M. Vogel
Menthol is effective at stimulating thermosensitive neurons that evoke pleasant cooling sensations. Internal application of menthol can be ergogenic for athletes, and hence, addition of menthol to sports nutrition products may be beneficial for athletes. The aim of this study was to develop a menthol energy gel for consumption during exercise and to determine acceptability and preferences for gels with different menthol concentrations. With a randomized, crossover, and double-blind placebo-controlled design, 40 endurance athletes (20 females) ingested an energy gel with a menthol additive at a high (0.5%; HIGH) or low concentration (0.1%; LOW), or a mint-flavored placebo (CON), on separate occasions during outdoor endurance training sessions. The athletes rated the gels for cooling sensation, mint flavor intensity, sweetness, and overall experience and provided feedback. Results are reported as median (interquartile range). Both menthol gels successfully delivered a cooling sensation, with a significantly greater response for HIGH (5.0 [4.0–5.0]) compared with LOW (3.5 [3.0–4.0]; p = .022) and CON (1.0 [1.0–2.0]; p < .0005), and LOW compared with CON (p < .0005). Ratings of mint flavor intensity followed the same trend as cooling sensation, while ratings of overall experience were significantly worse for HIGH (2.0 [1.0–3.0]) compared with LOW (4.0 [2.0–4.0]; p = .001) and CON (4.0 [3.0–4.0]; p < .0005). An energy gel with the addition of menthol at 0.1–0.5% provides a cooling sensation for athletes with a dose–response when ingested during exercise. The 0.1% concentration is recommended to maximize the overall experience of the gel.
Mariana B. Pinto, Patrícia M. Bock, Andressa S.O. Schein, Juliana Portes, Raíssa B. Monteiro, Beatriz D. Schaan and Beatriz D. Schaan
This study evaluated the effects of inspiratory muscle training (IMT) in glucose control and respiratory muscle function in patients with diabetes. It was a randomized clinical trial conducted at the Physiopathology Laboratory of the Hospital de Clínicas de Porto Alegre. Patients with Type 2 diabetes were randomly assigned to IMT or placebo-IMT (P-IMT), performed at 30% and 2% of maximal inspiratory pressure, respectively, every day for 12 weeks. The main outcome measures were HbA1c, glycemia, and respiratory muscle function. Thirty patients were included: 73.3% women, 59.6 ± 10.7 years old, HbA1c 8.7 ± 0.9% (71.6 ± 9.8 mmol/mol), and glycemia 181.8 ± 57.8 mg/dl (10.5 ± 3.2 mmol/L). At the end of the training, HbA1c was 8.2 ±0.3% (66.1 ± 3.3 mmol/mol) and 8.7 ± 0.3% (71.6 ± 3.3 mmol/mol) for the IMT and P-IMT groups, respectively (p = .8). Fasting glycemia decreased in both groups with no difference after training although it was lower in IMT at 8 weeks: 170.0 ± 11.4 mg/dl(9.4 ± 0.6 mmol/L) and 184.4 ± 15.0 mg/dl (10.2 ± 0.8 mmol/L) for IMT and P-IMT, respectively (p < .05). Respiratory endurance time improved in the IMT group (baseline = 325.9 ± 51.1 s and 305.0 ± 37.8 s; after 12 weeks = 441.1 ± 61.7 s and 250.7 ± 39.0 s for the IMT and P-IMT groups, respectively; p < .05). Considering that glucose control did not improve, IMT should not be used as an alternative to other types of exercise in diabetes. Higher exercise intensities or longer training periods might produce better results. The clinical trials identifier is NCT 03191435.
Iván Peña-González, Alba Roldan, Carlos Toledo, Tomás Urbán and Raúl Reina
Purpose: This study aimed (1) to explore the validity and reliability of a new and specific change-of-direction (COD) test that requires dribbling skills to classify international footballers with cerebral palsy (CP) and compare it with another valid and reliable COD test without ball dribbling and (2) to probe whether both tests can discriminate between the new CP football classes (ie, FT1, FT2, and FT3) established worldwide in 2018. Methods: This study involved 180 international para-footballers with CP from 23 national teams at the 3 regional competitions held in 2018. They performed 2 COD tests, the modified agility test (no dribbling skills) and the dribbling speed test (DST). Results: Reliability was excellent for both the modified agility test (intraclass correlation coefficient [ICC]2,1 = .91, SEM = 5.75%) and the DST (ICC2,1 = .92, SEM = 4.66%). The modified agility test and DST results were highly to very highly correlated to one another for the whole group and considering the sport classes (r = .60–.80; P < .001). A 1-way analysis of variance showed significant differences between sport classes in both tests (P < .001). However, among classes, there were significant differences between FT1 and FT2 and FT3 (P < .01, effect size = large) and low to moderate effect sizes between FT2 and FT3 for either test. Conclusion: The DST appears to be valid and reliable to classify CP football players within the new classification system. Regression analysis revealed that 18.2% of the variance in the new sport classes could be explained by the 2 examined tests.
Thomas A. Haugen, Felix Breitschädel, Håvard Wiig and Stephen Seiler
Purpose: To quantify possible differences in countermovement jump height across sport disciplines and sex in national-team athletes. Methods: In this cross-sectional study, 588 women (23  y, 66  kg) and 989 men (23  y, 82  kg) from 44 different sport disciplines (including 299 medalists from European Championships, World Championships, and/or Olympic Games) tested a countermovement jump on a force platform at the Norwegian Olympic Training Center between 1995 and 2018. Results: Athletic sprinting showed the highest values among the men (62.7 [4.8] cm) and women (48.4 [6.0] cm), clearly ahead of the long jump/triple jump (mean difference ± 90% CL: 6.5 ± 5.0 and 4.3 ± 4.1; very likely and likely; moderate) and speed skating sprint (11.4 ± 3.1 and 7.5 ± 5.5 cm; most likely and very likely; very large and moderate). These horizontally oriented sports displayed superior results compared with more vertically oriented and powerful sports such as beach volleyball, weightlifting, and ski jumping, both in men (from 2.9 ± 4.7 to 15.6 ± 2.9 cm; small to very large; possibly to most likely) and women (5.9 ± 4.8 to 13.4 ± 3.4 cm; large to very large; very likely to most likely), while endurance sports and precision sports were at the other end of the scale. Overall, the men jumped 33% higher than the women (10.3, ±0.6 cm; most likely; large). Conclusions: This study provides practitioners and scientists with useful information regarding the variation in countermovement jump height among national-team athletes within and across sport disciplines.
Wigand Poppendieck, Melissa Wegmann, Anne Hecksteden, Alexander Darup, Jan Schimpchen, Sabrina Skorski, Alexander Ferrauti, Michael Kellmann, Mark Pfeiffer and Tim Meyer
Purpose: Cold-water immersion is increasingly used by athletes to support performance recovery. Recently, however, indications have emerged suggesting that the regular use of cold-water immersion might be detrimental to strength training adaptation. Methods: In a randomized crossover design, 11 participants performed two 8-week training periods including 3 leg training sessions per week, separated by an 8-week “wash out” period. After each session, participants performed 10 minutes of either whole-body cold-water immersion (cooling) or passive sitting (control). Leg press 1-repetition maximum and countermovement jump performance were determined before (pre), after (post) and 3 weeks after (follow-up) both training periods. Before and after training periods, leg circumference and muscle thickness (vastus medialis) were measured. Results: No significant effects were found for strength or jump performance. Comparing training adaptations (pre vs post), small and negligible negative effects of cooling were found for 1-repetition maximum (g = 0.42; 95% confidence interval [CI], −0.42 to 1.26) and countermovement jump (g = 0.02; 95% CI, −0.82 to 0.86). Comparing pre versus follow-up, moderate negative effects of cooling were found for 1-repetition maximum (g = 0.71; 95% CI, −0.30 to 1.72) and countermovement jump (g = 0.64; 95% CI, −0.36 to 1.64). A significant condition × time effect (P = .01, F = 10.00) and a large negative effect of cooling (g = 1.20; 95% CI, −0.65 to 1.20) were observed for muscle thickness. Conclusions: The present investigation suggests small negative effects of regular cooling on strength training adaptations.