Effects of exercise on glycemic control and body mass in type 2 diabetes mellitus: a meta-analysis of controlled clinical trials

Acclimatization to moderate high altitude accompanied by training at low altitude (living high–training low) has been shown to improve sea level endurance performance in accomplished, but not élite, runners. Whether élite athletes, who may be closer to the maximal structural and functional adaptive capacity of the respiratory (i.e. oxygen transport from environment to mitochondria) system, may achieve similar performance gains is unclear. To answer this question, we studied 14 élite men and eight élite women before and after 27 days of living at 2500 m while performing high‐intensity training at 1250 m. The altitude sojourn began 1 week after the USA Track and Field National Championships, when the athletes were close to their season's fitness peak. Sea level 3000‐m time trial performance was significantly improved by 1.1% (95% confidence limits 0.3–1.9%). One‐third of the athletes achieved personal best times for the distance after the altitude training camp. The improvement in running performance was accompanied by a 3% improvement in maximal oxygen uptake (72.1 ± 1.5–74.4 ± 1.5 ml kg^{? 1} min^{? 1}). Circulating erythropoietin levels were near double initial sea level values 20 h after ascent (8.5 ± 0.5–16.2 ± 1.0 IU ml^?1). Soluble transferrin receptor levels were significantly elevated on the 19th day at altitude, confirming a stimulation of erythropoiesis (2.1 ± 0.7–2.5 ± 0.6 μ g ml^‐1). Hb concentration measured at sea level increased 1 g dl^?1 over the course of the camp (13.3 ± 0.2–14.3 ± 0.2 g dl^?1). We conclude that 4 weeks of acclimatization to moderate altitude, accompanied by high‐intensity training at low altitude, improves sea level endurance performance even in élite runners. Both the mechanism and magnitude of the effect appear similar to that observed in less accomplished runners, even for athletes who may have achieved near maximal oxygen transport capacity for humans.     

Testosterone and cortisol in 93 elite road cyclists during a 10-day stage race: relationship with final ranking

Cycling stage racing is a heavy and strenuous endurance event and it has been recognized that such exercise can affect the hormonal asset of hypothalamic–pituitary–adrenal (HPA) and hypothalamic–pituitary–testicular (HPT) axis. However, in cycling, literature on such changes is scarce and published data have been derived from small samples of athletes. The aims of study were to provide normative values for serum hormonal steroid values, changes in serum hormonal steroids and assess any relationships between a riders’ performance and their hormonal profile before and after the stage race. Male elite professional cyclists (n = 93) competing in the 2010 GiroBio 10-day stage race participated in this study. Blood chemistry measurements included cortisol (C), testosterone (T), free testosterone (fT) and sex hormone binding globulin (SHBG). Data are expressed as mean ± SD. Serum concentration of C and fT were lower at the end of GiroBio [C (nmol L^?1): 559.34 ± 95.71 vs 469.59 ± 51.12; fT (pmol ml^?1): 63.91 ± 27.85 vs 37.51 ± 17.86]. These serum hormonal (mean values ± 2SD) values may be near the physiological ceiling for elite cyclists. There was inverse correlation among average final speed and pre-competition serum concentration of T (r = ?0.265, p = 0.01); average final speed was negatively correlated with riders body mass pre and post the 10-day stage event. In conclusion, pre-GiroBio serum C levels could be a useful benchmark to preserve riders’ health and, moreover, our data confirm that the strenuous effort sustained by riders during a stage race induces appreciable changes in the hormonal profile. In addition, our data suggest that lower levels of T could represent favourable prerequisite to cope better in a cycling stage race.     

Adaptation to a ketogenic diet modulates adaptive and mucosal immune markers in trained male endurance athletes

This study examined the effect of short‐term adaptation to a ketogenic diet (KD) on resting and post‐exercise immune markers. Using a randomized, repeated‐measures, crossover design, eight trained, male, endurance athletes ingested a 31‐day low carbohydrate (CHO), KD (energy intake: 4% CHO; 78% fat) or their habitual diet (HD) (energy intake: 43% CHO; 38% fat). On days 0 and 31, participants ran to exhaustion at 70% VO_2max. A high‐CHO (2 g·kg^?1) meal was ingested prior to the pre‐HD, post‐HD, and pre‐KD trials, with CHO (~55 g·h^?1) ingested during exercise, whereas a low‐CHO (<10 g) meal was ingested prior to the post‐KD trial, with fat ingested during exercise. Blood and saliva samples were collected at pre‐exercise, exhaustion, and 1 hour post‐exhaustion. T‐cell‐related cytokine gene expression within peripheral blood mononuclear cells (PBMCs) and whole‐blood inflammatory cytokine production were determined using 24‐hour multi‐antigen‐stimulated whole‐blood cultures. Multi‐antigen‐stimulated PBMC IFN‐γ mRNA expression and the IFN‐γ/IL‐4 mRNA expression ratio were higher at exhaustion in the post‐KD compared with pre‐KD trial (P = 0.003 and P = 0.004); however, IL‐4 and IL‐10 mRNA expression were unaltered (P > 0.05). Multi‐antigen‐stimulated whole‐blood IL‐10 production was higher in the post‐KD compared with pre‐KD trial (P = 0.028), whereas IL‐1β, IL‐2, IL‐8, and IFN‐γ production was lower in the post‐HD compared with pre‐HD trial (P < 0.01). Salivary immunoglobulin A (SIgA) secretion rate was higher in the post‐KD compared with pre‐KD trial (P < 0.001). In conclusion, short‐term adaptation to a KD in endurance athletes may alter the pro‐ and anti‐inflammatory immune cell cytokine response to a multi‐antigen in vitro and SIgA secretion rate.     

Acute and sustained effects of a periodized carbohydrate intake using the sleep‐low model in endurance‐trained males

Repeated periodization of carbohydrate (CHO) intake using a diet‐exercise strategy called the sleep‐low model can potentially induce mitochondrial biogenesis and improve endurance performance in endurance‐trained individuals. However, more studies are needed to confirm the performance‐related effects and to investigate the sustained effects on maximal fat oxidation (MFO) rate and proteins involved in intramuscular lipid metabolism. Thirteen endurance‐trained males (age 23‐44 years; O₂‐max, 63.9 ± 4.6 mL·kg^?1·min^?1) were randomized into two groups: sleep‐low (LOW‐CHO) or high CHO availability (HIGH‐CHO) in three weekly training blocks over 4 weeks. The acute metabolic response was investigated during 60 minutes of exercise within the last 3 weeks of the intervention. Pre‐ and post‐intervention, 30‐minute time‐trial performance was investigated after a 90‐minute pre‐load, which as a novel approach included nine intense intervals (and estimation of MFO). Additionally, muscle biopsies (v. lateralis) were obtained to investigate expression of proteins involved in intramuscular lipid metabolism using Western blotting. During acute exercise, average fat oxidation rate was ~36% higher in LOW‐CHO compared to HIGH‐CHO (P = .03). This did not translate into sustained effects on MFO. Time‐trial performance increased equally in both groups (overall time effect: P = .005). We observed no effect on intramuscular proteins involved in lipolysis (ATGL, G0S2, CGI‐58, HSL) or fatty acid transport and β‐oxidation (CD‐36 and HAD, respectively). In conclusion, the sleep‐low model did not induce sustained effects on MFO, endurance performance, or proteins involved in intramuscular lipid metabolism when compared to HIGH‐CHO. Our study therefore questions the transferability of acute effects of the sleep‐low model to superior sustained adaptations.     

A 11‐day compressed overload and taper induces larger physiological improvements than a normal taper in elite cyclists

Endurance athletes usually achieve performance peaking with 2‐4 weeks of overload training followed by 1‐3 weeks of tapering. With a tight competition schedule, this may not be appropriate. Thus, the aim of this study was to compare the effect of a compressed variant of the recommended overload and tapering approach (EXP; n = 9, VO_2peak = 77 ± 5 mL·min^?1·kg^?1) with a 11‐day traditional taper that maintained the usual frequency of high‐intensity aerobic interval training (HIT) and reduced the duration of training at lower exercise intensity (TRAD, n = 8, VO_2peak = 74 ± 4 mL·min^?1·kg^?1) on physiological and psychological variables of endurance performance. EXP performed a 6‐day period with daily HIT followed by a 5‐day step taper. Testing was performed before the intervention (pre), on the 7th (post‐1), and on the 11th day of the intervention (post‐2). From pre to post‐2, EXP achieved a larger relative improvement than TRAD in VO_2peak (4.0 ± 3.7% vs 0.8 ± 1.8%, respectively, P = .041) and the 1‐min peak power output from the VO_2peak test (5.0 ± 3.6% vs 0.9 ± 1.5%, respectively, P = .009) and had a tendency toward larger improvement in power output at a blood lactate concentration of 4 mmol?L^?1 (P = .088) and peak isokinetic knee extension (P = .06). The effect size of the relative improvement in the endurance variables revealed a moderate‐to‐large effect of EXP vs TRAD. In conclusion, this study indicates that elite cyclists performing the present 11‐day compressed performance peaking protocol consisting of a 6‐day HIT overload followed by a 5‐day step taper are superior to a 11‐day taper only.     

Effective microorganism – X attenuates circulating superoxide dismutase following an acute bout of intermittent running in hot,humid conditions

This study determined the effectiveness of antioxidant supplementation on high-intensity exercise-heat stress. Six males completed a high-intensity running protocol twice in temperate conditions (TEMP; 20.4°C), and twice in hot conditions (HOT; 34.7°C). Trials were completed following7 days supplementation with 70 ml·day^?1 effective microorganism-X (EM-X; TEMP_EMX or HOT_EMX) or placebo (TEMP_PLA or HOT_PLA). Plasma extracellular Hsp72 (eHsp72) and superoxide dismutase (SOD) were measured by ELISA. eHsp72 and SOD increased pre-post exercise (p < 0.001), with greater eHsp72 (p < 0.001) increases observed in HOT (+1.5 ng·ml^?1) compared to TEMP (+0.8 ng·ml^?1). EM-X did not influence eHsp72 (p > 0.05). Greater (p < 0.001) SOD increases were observed in HOT (+0.22 U·ml^?1) versus TEMP (+0.10 U·ml^?1) with SOD reduced in HOT_EMX versus HOT_PLA (p = 0.001). Physiological and perceptual responses were all greater (p < 0.001) in HOT versus TEMP conditions, with no difference followed EM-X (p > 0.05). EM-X supplementation attenuated the SOD increases following HOT, potentiating its application as an ergogenic aid to ameliorate oxidative stress.     

The relationship between brain-derived neurotrophic factor,irisin and cognitive skills of endurance athletes

Objective: The objective of this study was to assess the cognitive performance of endurance athletes and its relation with circulating brain-derived neurotrophic factor (BDNF) and irisin levels.

Methods: 26 endurance athletes (14 elite orienteers (mean ± SD: age = 26.33 ± 4.08, body weight = 70.33 ± 4.64, body height = 177.7 ± 6.1), 12 pentathletes (mean ± SD: age = 29.42 ± 5.32, body weight = 74.77 ± 6.59, body height = 180.8 ± 3.8)) and ten sedentary (mean ± SD: age = 27.30 ± 2.06, body weight = 76.65 ± 12.50, body height = 176.9 ± 5.2) men at almost same ages and educational levels participated in this study. Cognitive functions were analyzed with mini-mental-state examination (MMSE) and Isaacs’ Set Test of Verbal Fluency (IST) tests. Insulin-like growth factor-1 (IGF-1), BDNF and irisin levels were measured in the blood samples.

Results: The MSSE and IST scores of the endurance athletes were higher than that of the sedentary control group (P < 0.05). Serum IGF-1 levels were higher in the pentathletes (111.18 ± 22.26 ng mL^?1) than the orienteers (85.89 ± 19.32 ng mL^?1) (P < 0.05). Plasma BDNF (2.78 ± 0.81, 4.28 ± 1.03, and 3.93 ± 0.77 ng mL^?1 in the sedentary, orienteers and pentathletes, respectively) and irisin (3.25 ± 0.70, 6.16 ± 0.99, and 6.58 ± 1.09 µg mL^?1 in the sedentary, orienteers and pentathletes, respectively) concentrations of the endurance trained athletes were higher than that of the sedentary control group (P < 0.05). Positive correlation between the cognitive function test results and BDNF and irisin concentrations were observed (P < 0.05). There was also a positive correlation between the circulating irisin and BDNF concentrations (P < 0.05).

Conclusion: These results suggested that irisin and BDNF levels positively correlated with cognition in the endurance trained athletes.     

High dose Nitrate ingestion does not improve 40 km cycling time trial performance in trained cyclists

ABSTRACT

This study evaluated the chronic effects of nitrate (NO₃^?) ingestion over three days, on 40 km TT performance in 11trained cyclists (VO_2max: 60.8 ± 7.4 ml.kg^?1.min^?1; age: 36 ± 9 years; height: 1.80 ± 0.06 m; body mass: 87.2 ± 12.0 kg). Utilising a double-blind randomised cross-over design, participants completed three 40 km TT on a Velotron® ergometer following the ingestion of either a 140 ml of “BEET It sport®” NO₃^? shot containing 12.8 mmol or 800 mg of NO₃^?, a placebo drink or nothing (control). Performance, oxygen consumption (VO₂), blood bicarbonate (HCO3-), pH and lactate (BLa) and ratings of perceived exertion (RPE) were measured every 10 km throughout the TT. The present findings show that NO₃^? ingestion had no effect on TT performance (NO₃^?: 4098.0 ± 209.8 vs. Placebo: 4161.9 ± 263.3 s, p = 0.296, ES = 0.11), or VO₂ (p = 0.253, ES = 0.13). Similarly, blood lactate and RPE were also unaffected by the experimental conditions (p = 0.522, ES = 0.06; p = 0.085, ES = 0.30) respectively. Therefore, these results suggest that a high dose of NO₃^? over three days has limited efficacy as an ergogenic aid for 40 km TT cycling performance in trained cyclists.     

Aspects of leukocyte function and the complement system following aeeorbic exercise in young female gymnasts*

Recent studies have reported reduced immunity in trained athletes. Scant information exists on changes in the immune function among trained children. The purpose of this study was to assess the effect of aerobic exercise on the phagocytic process of neutrophils and the complement system in young athletes. Subjects included prepubertal elite female gymnasts (n=7) and untrained girls (n=6) aged 10–12 years. Venous blood was withdrawn before, immediately post and 24 h following a 20-min run at a heart rate of 170–180 beats · min^?1. Neutrophil random migration, chemotactic activity, bactericidal function and PMA/FMLP-stimulated superoxide anion release as well as various complement components were assessed. Net chemotaxis was found reduced (P<0.05) 24 h following exercise (58±11 vs. 36±11 cells/field in gymnasts and 47±7 vs. 42±8 cells/field in untrained girls pre and 24 h post-exercise, respectively). The basal values, as well as post-exercise values of bactericidal activity were lower ((P<0.05) in gymnasts as compared with the control group (0.8±0.3, 0.8±0.2 and 0.8±0.2 log decrease of colonies in gymnasts at pre^?, immediately post^?, and 24 h post-exercise, respectively and 11±0.1, 1.1±0.1 and 1.0±0.2 log decrease of colonies in controls, respectively). No significant effect on the bactericidal activity was observed in either group following exercise. The addition of homologous sera did not correct the bactericidal activity. PMA-stimulated superoxide anion release decreased (P<0.05) among gymnasts immediately following exercise (5.7±0.4 vs. 4.4± 1.0 mmol 0₂/10⁶ PMN · min) and remained low 24 h later. The same trend was observed in FMLP-stimulated neutrophils but the data were not significant. Significantly decreased levels (P<0.05) of the early complement components (ClQ, C1R) were also found following exercise (1±0.64 vs. 1.27±0.28 and 1.09±0.07 vs. 1.02±0.06 pre- and postexercise in gymnasts and untrained, respectively). Furthermore, consistently lower C2 and C3 were observed in gymnasts compared with controls. Neutrophil dysfunction as well as impairment of the complement system seem to occur following exercise.     

Skeletal muscle water and electrolytes following prolonged dehydrating exercise

We studied if dehydrating exercise would reduce muscle water (H₂O_muscle) and affect muscle electrolyte concentrations. Vastus lateralis muscle biopsies were collected prior, immediately after, and 1 and 4 h after prolonged dehydrating exercise (150 min at 33 ± 1 °C, 25% ± 2% humidity) on nine endurance‐trained cyclists (VO_2max = 54.4 ± 1.05 mL/kg/min). Plasma volume (PV) changes and fluid shifts between compartments (Cl^? method) were measured. Exercise dehydrated subjects 4.7% ± 0.3% of body mass by losing 2.75 ± 0.15 L of water and reducing PV 18.4% ± 1% below pre‐exercise values (P < 0.05). Right after exercise H₂O_muscle remained at pre‐exercise values (i.e., 398 ± 6 mL/100 g dw muscle^?1) but declined 13% ± 2% (342 ± 12 mL/100 g dw muscle^?1; P < 0.05) after 1 h of supine rest. At that time, PV recovered toward pre‐exercise levels. The Cl^? method corroborated the shift of fluid between extracellular and intracellular compartments. After 4 h of recovery, PV returned to pre‐exercise values; however, H₂O_muscle remained reduced at the same level. Muscle Na⁺ and K⁺ increased (P < 0.05) in response to the H₂O_muscle reductions. Our findings suggest that active skeletal muscle does not show a net loss of H₂O during prolonged dehydrating exercise. However, during the first hour of recovery H₂O_muscle decreases seemly to restore PV and thus cardiovascular stability.     

The efficacy of weekly and bi-weekly heat training to maintain the physiological benefits of heat acclimation

ObjectivesTo examine the efficacy of weekly and bi-weekly heat training to maintain heat acclimatization (HAz) and heat acclimation (HA) for 8 weeks in aerobically trained athletes.DesignRandomized, between-group.MethodsTwenty-four males (mean [m ± standard deviation [sd]; (age, 34 ± 12 y; body mass, 72.6 ± 8.8 kg, VO_2peak, 57.7 ± 6.8 mL·kg^?1·min^?1) completed five trials (baseline, following HAz, following HA (HAz + HA), four weeks into heat training [HT_WK4], and eight weeks into HT [HT_WK8] that involved 60 min of steady-state exercise (59.1 ± 1.8% vVO_2peak) in an environmental laboratory (wet bulb globe temperature [WBGT], 29.6 ± 1.4 °C) on a motorized treadmill. Throughout exercise, heart rate (HR) and rectal temperature (T_rec) were recorded. Following HAz + HA, participants were assigned to three groups: control group (HT₀), once per week heat training (HT₁), and twice per week heat training (HT₂). HT involved heated exercise (WBGT, 33.3 ± 1.3 °C) to achieve hyperthermia (38.5–39.75 °C) for 60 min. Repeated measures ANOVAs were used to determine differences.ResultsHAz + HA resulted in significant improvements in HR (p < 0.001) and T_rec (p < 0.001). At HT_WK8, HR was significantly higher in HT₀ (174 ± 22 beats?min^?1) compared to HT₂ (151 ± 17 beats?min^?1, p < 0.023), but was not different than HT₁ (159 ± 17 beats?min^?1, p = 0.112). There was no difference in % change of T_rec from post-HAz + HA to HT_WK4 (0.6 ± 1.3%; p = 0.218), however, HT_WK8 (1.8 ± 1.4%) was significantly greater than post-HAz + HA in HT₀ (p = 0.009).ConclusionsBi-weekly HT provided clear evidence for the ability to maintain physiological adaptions for 8 weeks following HA.     

Letter to the Editor

The relative biological effectiveness (RBE) of selected low-LET radiation modalities (55 kVp X-rays, 250 kVp X-rays, ⁶⁰Co γ-rays, and 11 MeV electrons) was investigated for survival of two cell lines (V79 and CHO). Detailed measurements were made in the low (0 to 3 Gy) dose range using an image cytometry device to accurately determine the number of cells assayed at each dose point. Data were also collected in the high dose range (0 to 10 Gy) using conventional counting and plating techniques. RBE values (± 1 SE) varied from 1·0 ± 0·07 (V79 cells) and 1·2 ± 0·05 (CHO cells) at high doses to 1·3 ± 0·07 (V79) and 1·4 ± 0·1 (CHO) at low doses for 55 kVp X-rays, from 1·1 ± 0·05 (V79) and 1·1 ± 0·04 (CHO) at high doses to 1·1 ± 0·06 (V79) and 1·2 ± 0·2 (CHO) at low doses for 250 kVp X-rays, and from 1·1 ± 0·08 (V79) and 1·0 ± 0·04 (CHO) at high doses to 1·0 ± 0·06 (V79) and 0·9 ± 0·1 (CHO) at low doses for 11 MeV electrons. Only the low and high dose RBEs for 55 kVp X-rays relative to ⁶⁰Co γ-rays were significantly different.     

No effect of dietary nitrate supplementation on endurance training in hypoxia

We investigated whether dietary nitrate (NO₃^?) supplementation enhances the effect of training in hypoxia on endurance performance at sea level. Twenty‐two healthy male volunteers performed high‐intensity endurance training on a cycle ergometer (6 weeks, 5×30 min/week at 4–6 mmol/L blood lactate) in normobaric hypoxia (12.5% FiO₂), while ingesting either beetroot juice [0.07 mmol NO₃^?/kg body weight (bw)/day; BR, n = 11] or a control drink (CON, n = 11). During the pretest and the posttest, the subjects performed a 30‐min simulated time trial (TT) and an incremental VO_2max test. Furthermore, a biopsy was taken from m. vastus lateralis before and after the TT. Power output during the training sessions in both groups increased by ～6% from week 1 to week 6 (P < 0.05). Compared with the pretest, VO_2max in the posttest was increased (P < 0.05) in CON (5%) and BR (9%). Power output corresponding with the 4 mmol/L blood lactate threshold, as well as mean power output during TT increased by ～16% in both groups (P < 0.05). Muscle phospho‐AMP‐activated protein kinase, hypoxia inducible factor‐1α mRNA content, and glycogen breakdown during the TT were similar between the groups in both the pretest and the posttest. In conclusion, low‐dose dietary NO₃^? supplementation does not enhance the effects of intermittent hypoxic training on endurance exercise performance at sea level.     

Evaluation of critical swimming velocity in young amateur swimmers

The purpose of this study was to compare in amateur swimmers the critical swimming velocity (CV) with the swimming velocity corresponding to a blood lactate concentration of 4 mmol l^?1 (V ₄). Ten amateur swimmers volunteered for this study (six men, age 22.3 ± 2 years; four women, age 21.3 ± 1 years) and performed a 7 × 200-m swimming test (at 70%, 75%, 80%, 85%, 90%, 95% and 100% of their 200-m best time) with 5 min rest between each repetition. Blood lactate concentration was determined after each repetition. V ₄ was determined from the speed-lactate curve. In order to calculate CV, the best front-crawl swimming results over 50, 100, 200 and 400 m were used. CV was expressed as the slope of the linear relationship between time and distance. Swimming velocities obtained with the two tests (CV 1.086 ± 0.151 m s^?1; V ₄ 1.087 ± 0.128 m s^?1) were positively and significantly correlated (r = 0.93, p < 0.05) and no significant differences were found. A Bland-Altman plot showed a good agreement between the two measurement methods. These results confirm that the CV seems to be a valid and noninvasive method for also determining training intensities and monitor endurance capacity in less-experienced athletes.     

Two weeks of repetitive gut‐challenge reduce exercise‐associated gastrointestinal symptoms and malabsorption

Debilitating gastrointestinal symptoms is a common feature of endurance running and may be exacerbated by and/or limit the ability to tolerate carbohydrate intake during exercise. The study aimed to determine whether two weeks of repetitive gut‐challenge during running can reduce exercise‐associated gastrointestinal symptoms and carbohydrate malabsorption. Endurance runners (n =18) performed an initial gut‐challenge trial (GC 1) comprising 2‐hour running exercise at 60% VO _2max (steady state) while consuming a formulated gel‐disk containing 30 g carbohydrates (2:1 glucose‐fructose, 10% w/v ) every 20 minutes, followed by a 1‐hour running effort bout. Gastrointestinal symptoms, feeding tolerance, and breath hydrogen (H₂) were determined along the gut‐challenge trial. After GC 1, participants were randomly assigned to a blinded carbohydrate (CHO , 90 gCHO  hour⁻¹) or placebo (PLA , 0 gCHO  hour⁻¹) gut‐training group. This comprised of consuming the group‐specific feeding intervention during 1‐hour running exercise at 60% VO _2max equivalent, daily over a period of two weeks. Participants then repeated the gut‐challenge trial (GC 2). In GC 2, a reduced gut discomfort (P =.012), total (P =.009), upper‐ (P =.015), and lower‐gastrointestinal (P =.008) symptoms, and nausea (P =.05) were observed on CHO , but not PLA . Feeding tolerance did not differ between GC 1 and GC 2 on CHO and PLA . H₂ peak was attenuated in GC 2 (6±3 ppm) compared to GC 1 (13±6 ppm) on CHO (P =.004), but not on PLA (GC 1 11±7 ppm, and GC 2 10±10 ppm). The effort bout distance was greater in GC 2 (12.3±1.3 km) compared with GC 1 (11.7±1.5 km) on CHO (P =.035) only. Two weeks of repetitive gut‐challenge improve gastrointestinal symptoms and reduce carbohydrate malabsorption during endurance running, which may have performance implications.     

Effects of acute and 2‐week administration of oral salbutamol on exercise performance and muscle strength in athletes

Our objective was to investigate effects of acute and 2‐week administration of oral salbutamol on repeated sprint ability, exercise performance, and muscle strength in elite endurance athletes. Twenty male elite athletes [VO_2max: 69.4 ± 1.8 (Mean ± SE) mL/min/kg], aged 25.9 ± 1.4 years, were included in a randomized, double‐blinded and placebo‐controlled parallel study. At baseline, after acute administration, and again after 2‐week administration of the study drugs (8 mg salbutamol or placebo), subjects' maximal voluntary contraction (MVC) of m. quadriceps and isometric endurance of m. deltoideus were measured, followed by three repeated Wingate tests. Exercise performance at 110% of VO_2max was determined on a bike ergometer. Acute administration of salbutamol increased peak power during first Wingate test by 4.1 ± 1.7% (P < 0.05). Two‐week administration of salbutamol increased (P < 0.05) peak power during first and second Wingate test by 6.4 ± 2.0 and 4.2 ± 1.0%. Neither acute nor 2‐week administration of salbutamol had any effect on MVC, exercise performance at 110% of VO_2max or on isometric endurance. No differences were observed in the placebo group. In conclusion, salbutamol benefits athletes' sprint ability. Thus, the present study supports the restriction of oral salbutamol in competitive sports.     

Foam rolling is an effective recovery tool in trained distance runners

Purpose

Many endurance athletes use foam rolling (FR) to decrease muscle soreness, but it is unclear whether FR effectively treats soreness in this population. Moreover, the effects of FR in highly trained runners are unknown. The aim of this study was to use downhill running (DHR) to induce muscle soreness in runners and to determine the influence of FR on soreness and running performance when compared to sham compression tights.

Methods

Participants performed a running economy (RE) test at 75% of 5-km race speed and a 3-km time trial (TT). In a crossover design, subjects then completed DHR followed by either a FR protocol or wearing sham compression tights. Two days post-DHR, subjects repeated the RE and TT tests. Crossover visits occurred 2–4 weeks later. During RE tests, VO₂ and rating of perceived exertion (RPE) were recorded. Passive and active soreness were measured on a scale of 0 (no soreness) to 10 (extreme soreness).

Results

Eight runners (aged 31?±?7 years; four females; VO_2peak 57?±?7 ml kg^?1 min^?1) completed the study. Both treatment conditions experienced passive (p?=?0.026) and active soreness (p = 0.012) induced by DHR. Active soreness 2 days post-DHR was significantly lower after FR than after sham compression tights (p?=?0.025). With tights, there was a trend for an increased RPE compared to pre-DHR (p?=?0.056).

Conclusions

Foam rolling decreases leg soreness in well-trained runners and attenuates soreness-related increases in perceived exertion during sub-maximal running.

     

Determination and validation of peak fat oxidation in endurance‐trained men using an upper body graded exercise test

Peak fat oxidation rate (PFO) and the intensity that elicits PFO (Fat_max) are commonly determined by a validated graded exercise test (GE) on a cycling ergometer with indirect calorimetry. However, for upper body exercise fat oxidation rates are not well elucidated and no protocol has been validated. Thus, our aim was to test validity and inter‐method reliability for determination of PFO and Fat_max in trained men using a GE protocol applying double poling on a ski‐ergometer. PFO and Fat_max were assessed during two identical GE tests (GE1 and GE2) and validated against separated short continuous exercise bouts (SCE) at 35%, 50%, and 65% of V?O_2peak on the ski‐ergometer in 10 endurance‐trained men (V?O_2peak: 65.1 ± 1.0 mL·min^?1·kg^?1, mean ± SEM). Between GE tests no differences were found in PFO (GE1: 0.42 ± 0.03; GE2: 0.45 ± 0.03 g·min^?1, P = .256) or Fat_max (GE1: 41 ± 2%; GE2: 43 ± 3% of V?O_2peak, P = .457) and the intra‐individual coefficient of variation (CV) was 8 ± 2% and 11 ± 2% for PFO and Fat_max, respectively. Between GE and SCE tests, PFO (GE_avg: 0.44 ± 0.03; SCE; 0.47 ± 0.06 g·min^?1, P = .510) was not different, whereas a difference in Fat_max (GE_avg: 42 ± 2%; SCE: 52 ± 4% of V?O_2peak, P = .030) was observed with a CV of 17 ± 4% and 15 ± 4% for PFO and Fat_max, respectively. In conclusion, GE has a high day‐to‐day reliability in determination of PFO and Fat_max in trained men, whereas it is unclear if PFO and Fat_max determined by GE reflect continuous exercise in general.     

Aerobic exercise capacity at sea level and at altitude in Kenyan boys, junior and senior runners compared with Scandinavian runners

The aim of this study was to characterize Kenyan runners in regard to their oxygen uptake and blood and ammonia responses when running. Untrained Kenyan boys (14.2±0.2 years) and Scandinavian runners were included for comparison. The studies were performed at altitude (～2.000 m.a.s.l.) and, for several Kenyan and Scandinavian runners, at sea level as well. At altitude sedentary adolescent Kenyan boys had a mean maximal oxygen uptake (Vo_2max) of 47 (44–51) ml · kg^?1· min^?1, whereas similarly aged boys regularly walking or running but not training for competition reached above 62 (58–71) ml · kg^?1· min^?1 in Vo^2max. Kenyan runners in active training had 68±1.4 ml · kg^?1· min^?1 at altitude and 79.9±1.4 ml · kg^?1· min^?1 at sea level, with individuals reaching 85 ml · kg^?1· min^?1. The best Scandinavian runners were not significantly different from the Kenyan runners in Vo_2max both at altitude and at sea level, but none of the Scandinavians reached as high individual values as observed for some Kenyan runners. The running efficiency, determined as the oxygen cost at a given running speed, was less in the Kenyan runners, and the difference became more pronounced when body weight was expressed in ml · kg^?0.75 min^?1. Blood lactate concentration was in general lower in the Kenyan than in the Scandinavian runners, and the Kenyans also had extremely low ammonia accumulation in the blood even at very high exercise intensities. It is concluded that it is the physical activity during childhood, combined with intense training as teenagers that brings about the high Vo_2max observed in some Kenyan runners. Their high aerobic capacity, as well as their good running economy, makes them such superior runners. In addition, their low blood lactate and ammonia accumulation in blood when running may also be contributing factors.