Well-trained Male Runners Research Articles

Physiological Responses in Trail Runners during a Maximal Test with Different Weighted-Vest Loads.

During some trail running races, athletes have to carry hydration support, food, and technical and safety equipment, which generates an additional load that must be mobilized during the race. The aim of the present study was to determine the physiological responses to overload running and the effect they may have on metabolic zones. Seventeen well-trained male trail runners (n = 17) completed three maximal treadmill tests with weighted vests at 0%, 5%, and 10% of their body mass (L0, L5, and L10). Their gas exchange was monitored to assess their ventilatory thresholds 1 (VT1) and 2 (VT2), maximal fat oxidation zone (FatMax), and peak oxygen consumption (VO2peak). Their heart rate (HR), power, and velocity (V) were tracked to compare their behavior. One-way ANOVA showed significant differences in the V (p < 0.001; ηp2 = 0.4620) as a limitation for reaching the peak velocity (Vpeak), with a significant decrease in the Vpeak with the L10 compared to the L0 (p = 0.002) and L5 (p = 0.004). In addition, one-way ANOVA showed significant differences in the peak absolute power (p < 0.001; ηp2 = 0.468) among the groups, detecting higher power production between the L10 and L0 (p < 0.001) and between the L10 and L5 (p = 0.015). Loads higher than L5 could generated important physiological and mechanical modifications, while a load of L5 managed to maintain the working conditions without overloading. These insights shed light on nuanced strategies for optimizing performance and endurance, offering valuable considerations for athletes seeking to enhance their training regimens during overload conditions.

Durability of Running Economy: Differences between Quantification Methods and Performance Status in Male Runners.

Running economy (RE) deteriorates during prolonged running, although the effect of measuring energy cost (EC) or oxygen cost (OC) on the magnitude of these changes has not been investigated. Similarly, it is unknown if runners' performance level may influence the deterioration of RE during prolonged running. The aims of this study were to compare changes in EC and OC measurements of RE during a prolonged run in a large cohort of well-trained male runners, and to compare changes between runners of high- and low-performance standard. Forty-four male runners (maximal oxygen uptake (V̇O 2max ) 62.4 mL·kg -1 ·min -1 ; 10-km time: 35:50 ± 4:40 mm:ss) completed an incremental test determining lactate threshold 1 (LT1) and V̇O 2max , and on a separate occasion, a 90-min run at LT1. Respiratory gases were collected at 15-min intervals. Subsequently, subgroups of high- (HP; 10-km time: 31:20 ± 01:00 mm:ss) and low-performing (LP; 10-km time: 41:50 ± 01:20 mm:ss) runners were compared. RE deterioration was only fractionally larger when expressed as OC than EC (0.1% greater from 30-90 min; P < 0.001), perhaps due to the small change in respiratory exchange ratio (-0.01) in this study. For the HP group, increases were lower than LP after 90 min in both EC (+2.3% vs +4.3%; P < 0.01) and OC (+2.4% vs +4.5%; P < 0.01). Similarly, at standardized distances, changes were lower for HP versus LP, for example, at 16.7 km + 1.0 versus +3.2% for EC ( P < 0.01), and +1.2 vs +3.4% for OC ( P < 0.001). The deterioration of RE was dependent on athlete's performance level, with HP runners displaying superior RE durability. The use of EC or OC had only a fractional influence on RE durability, although this may gain importance with larger shifts in substrate metabolism.

Effects of three weeks base training at moderate simulated altitude with or without hypoxic residence on exercise capacity and physiological adaptations in well-trained male runners.

To test the hypothesis that 'live high-base train high-interval train low' (HiHiLo) altitude training, compared to 'live low-train high' (LoHi), yields greater benefits on performance and physiological adaptations. Sixteen young male middle-distance runners (age, 17.0 ± 1.5 y; body mass, 58.8 ± 4.9 kg; body height, 176.3 ± 4.3 cm; training years, 3-5 y; training distance per week, 30-60 km.wk-1) with a peak oxygen uptake averaging ~65 ml.min-1.kg-1 trained in a normobaric hypoxia chamber (simulated altitude of ~2,500 m, monitored by heart rate ~170 bpm; thrice weekly) for 3 weeks. During this period, the HiHiLo group (n = 8) stayed in normobaric hypoxia (at ~2,800 m; 10 h.day-1), while the LoHi group (n = 8) resided near sea level. Before and immediately after the intervention, peak oxygen uptake and exercise-induced arterial hypoxemia responses (incremental cycle test) as well as running performance and time-domain heart rate variability (5-km time trial) were assessed. Hematological variables were monitored at baseline and on days 1, 7, 14 and 21 during the intervention. Peak oxygen uptake and running performance did not differ before and after the intervention in either group (all P > 0.05). Exercise-induced arterial hypoxemia responses, measured both at submaximal (240 W) and maximal loads during the incremental test, and log-transformed root mean square of successive R-R intervals during the 4-min post-run recovery period, did not change (all P > 0.05). Hematocrit, mean reticulocyte absolute count and reticulocyte percentage increased above baseline levels on day 21 of the intervention (all P < 0.001), irrespective of group. Well-trained runners undertaking base training at moderate simulated altitude for 3 weeks, with or without hypoxic residence, showed no performance improvement, also with unchanged time-domain heart rate variability and exercise-induced arterial hypoxemia responses.

Impact of midsole thickness on physiological responses during running in well-trained athletes

Introduction Modern running shoes have revolutionized long-distance performances by decreasing the amount of oxygen athletes need when running at a given speed, which is termed running economy. In 2022, World Athletics imposed an upper limit of 40 mm for midsole thickness, possibly to prevent shoes from having an overemphasized role in performance. This ceiling, however, seems arbitrary, and a better understanding of whether midsole thickness affects running economy is needed. This study therefore investigated if midsole thickness affects oxygen consumption both indoors and outdoors, as early findings from treadmill studies may not translate to overground running. Methods Following a familiarization trial including an incremental test, 16 well-trained male runners (weight 70 ± 6 kg, age 28 ± 5 years, peak oxygen uptake, V̇O2peak 64 ± 4 ml O2･kg-1･min-1, peak running speed 20.0 ± 0.8 km･h-1) completed two testing visits, once on a treadmill and once on a track, each consisting of twelve 5-min runs at submaximal speed (16 km･h-1) alternating three different footwear conditions: an entry-level running shoe (EL, 30 mm midsole thickness) and two carbon-plated modern running shoes with midsole thickness of 40 and 50 mm, respectively. The shoe order was randomized and balanced between each of the four replicates. Gas exchange and heart rate were continuously measured throughout the runs. Results Running with 40 mm shoes reduced V̇O2 compared with EL shoes by 2.4 ± 1.1% on the treadmill and 4.0 ± 1.2% when running overground (both p &lt; 0.001). Running with 50mm shoes also decreased V̇O2 compared with EL shoes both on the treadmill (-2.7 ± 1.6%, p &lt; 0.001) and overground (-4.6 ± 1.8%, p &lt; 0.001), but no differences were detected between the modern shoes (40 mm vs. 50 mm treadmill: +0.3 ± 1.3%, p = 0.586; overground: +0.6 ± 1.4%, p = 0.189). Similarly, heart rate was lower compared with the EL shoes in both the 40 mm shoes (treadmill -1.3 ± 0.6%; overground -2.0 ± 0.6%; both p &lt; 0.001) and 50 mm shoes (treadmill -1.6 ± 0.7%; overground -2.3 ± 0.6%, both p &lt; 0.001), but no differences were detected between the modern shoes (40 mm vs. 50 mm treadmill: +0.3% ± 0.6%, p = 0.106; overground: +0.4 ± 0.6%, p = 0.090). Interestingly when running overground V̇O2 decreased over time for the 50 mm shoes, reaching significance between replicates 1 and 4 (p = 0.017), which was not the case for the 40 mm shoes (p = 0.817). The V̇O2 ratio between the 50 mm and 40 mm shoes was 1.003 in replicate 1 and 0.987 in replicate 4 (p = 0.108). Discussion/Conclusion Our data suggests that a 50 mm midsole does not offer significant benefits compared with race-legal 40 mm midsole shoes when tested over short durations. The 50 mm shoes cause a noticeable decrease in V̇O2 over time when used outdoors, which may reflect a learning effect to this unfamiliar midsole thickness. Longer test sessions may be necessary to reveal the actual impact on running economy of shoes with over 40 mm midsoles.

Flat Versus Simulated Mountain Trail Running: A Multidisciplinary Comparison in Well-Trained Runners

This paper compares cardiopulmonary and neuromuscular parameters across three running aerobic speeds in two conditions that differed from a treadmill's movement: flat condition (FC) and unpredictable roll variations similar to mountain trail running (URV). Twenty well-trained male runners (age 33 ± 8 years, body mass 70.3 ± 6.4 kg, height 1.77 ± 0.06 m, V˙O2max 63.8 ± 7.2 mL·kg-1·min-1) voluntarily participated in the study. Laboratory sessions consisted of a cardiopulmonary incremental ramp test (IRT) and two experimental protocols. Cardiopulmonary parameters, plasma lactate (BLa-), cadence, ground contact time (GT) and RPE values were assessed. We also recorded surface electromyographic (sEMG) signals from eight lower limb muscles, and we calculated, from the sEMG envelope, the amplitude and width of peak muscle activation for each step. Cardiopulmonary parameters were not significantly different between conditions (V˙O2: p = 0.104; BLa-: p = 0.214; HR: p = 0.788). The amplitude (p = 0.271) and width (p = 0.057) of sEMG activation peaks did not change between conditions. The variability of sEMG was significantly affected by conditions; indeed, the coefficient of variation in peak amplitude (p = 0.003) and peak width (p < 0.001) was higher in URV than in FC. Since the specific physical demands of running can differ between surfaces, coaches should resort to the use of non-traditional surfaces, emphasizing specific surface-related motor tasks that are normally observed in natural running environments. Seeing that the variability of muscle activations was affected, further studies are required to better understand the physiological effects induced by systematic surface-specific training and to define how variable-surface activities help injury prevention.

No Effect of EVA and TPU Custom Foot Orthoses on Mechanical Asymmetries during Acute Intense Fatigue

This study examined the impact of custom foot orthoses made of ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to a control condition (CON; shoes only), on mechanical asymmetries during repeated treadmill sprints. Eighteen well-trained male runners executed eight, 5-s sprints (rest: 25 s) on an instrumented motorized treadmill in three footwear conditions (EVA, TPU, and CON). We evaluated the group mean asymmetry scores using the ‘symmetry angle’ (SA) formula, which assigns a score of 0% for perfect symmetry and a score of 100% for perfect asymmetry. There was no condition (all p ≥ 0.053) or time (p ≥ 0.074) main effects, nor were there any significant time × condition interactions on SA scores for any variables (p ≥ 0.640). Mean vertical, horizontal, and total forces presented mean SA values (pooled values for the three conditions) of 2.6 ± 1.9%, 2.9 ± 1.6%, and 2.4 ± 1.8%, respectively. Mean SA scores were ~1–3% for contact time (1.5 ± 0.5%), flight time (3.0 ± 0.3%), step frequency (1.1 ± 0.5%), step length (1.9 ± 0.7%), vertical stiffness (2.1 ± 0.9%), and leg stiffness (2.4 ± 1.1%). Mean SA scores were ~2–6.5% for duration of braking (4.1 ± 1.6%) and propulsive (2.4 ± 1.0%) phases, and peak braking (6.2 ± 2.9%) and propulsive (2.1 ± 1.4%) forces. In well-trained runners facing intense fatigue, wearing custom foot orthoses did not modify the observed low-to-moderate natural stride mechanical asymmetries.

Influence of Recovery Mode on the Maximum Number of Intervals Until Exhaustion During an Aerobic Interval Training Session.

Varela-Sanz, A, Sánchez-Otero, T, Tuimil, JL, Boullosa, D, and Iglesias-Soler, E. Influence of recovery mode on the maximum number of intervals until exhaustion during an aerobic interval training session. J Strength Cond Res 37(9): e510-e520, 2023-We analyzed work capacity, cardiometabolic, perceptual, and neuromuscular responses to an aerobic interval training (AIT) running session until exhaustion, with active (AR) vs. passive recovery (PR). Eight well-trained male endurance runners (36.88 ± 7.14 years, 58.22 ± 3.39 ml·kg -1 ·minute -1 ) randomly completed, after familiarizations and the University of Montreal Track Test (UMTT), 2 AIT track running sessions until exhaustion consisting in 2-minute bouts at 100% of maximum aerobic speed (MAS), with 2 minutes of recovery at 80% of the velocity associated to the second ventilatory threshold (vVT 2 ) (i.e., AR), or no exercise (i.e., PR). Oxygen consumption (V̇O 2 ), heart rate (HR), blood lactate [La], rating of perceived exertion (RPE), and countermovement jump (CMJ) were continuously monitored during sessions. The level of statistical significance was set at p ≤ 0.05. PR resulted in longer time to exhaustion during sessions (13.9 vs. 11.6 bouts, p = 0.045), but lower HR ( p < 0.01) when compared with AR. Time spent over 90% of maximum oxygen consumption (V̇O 2max ), blood lactate concentrations, neuromuscular performance, and RPE did not differ between AR and PR ( p > 0.05). Thus, PR allowed runners to perform more work intervals and, therefore, to accumulate a greater volume. On the other hand, when training goals are focused on reaching a higher chronotropic stress (i.e., higher HR) during the training session, athletes would obtain more benefits from AR. This study also demonstrates that the current volume recommendations for AIT are far below (54-64.5%) the maximum training capacity of well-trained runners.

Increasing Shoe Longitudinal Bending Stiffness Is Not Beneficial to Reduce Energy Cost During Graded Running

Carbon plates have been used to increase running shoes' longitudinal bending stiffness (LBS), leading to reductions in the energy cost of level running (Cr). However, whether or not this is true during uphill (UH) running remains unknown. The aim of our study was to identify the effect of LBS on Cr during UH running. Twenty well-trained male runners participated in this study. Cr was determined using gas exchange during nine 4-minute bouts performed using 3 different LBS shoe conditions at 2.22 and 4.44m/s on level and 2.22m/s UH (gradient: + 15%) running. All variables were compared using 2-way analyses of variance (LBS × speed/grade effects). There was no significant effect of LBS (F = 2.04; P = .14, ηp2=.11) and no significant LBS × grade interaction (F = 0.31; P = .87, ηp2=.02). Results were characterized by a very large interindividual variability in response to LBS changes. The current study contributes to a growing body of literature reporting no effect of LBS on Cr during level and UH running. Yet, the very large interindividual differences in response to changes in LBS suggest that increasing shoe LBS may be beneficial for some runners.

Effects of plyometric training on different 8-week training intensity distributions in well-trained endurance runners.

The aim of this four-armed parallel group randomized-controlled trial was to evaluate if plyometric training could have different effects on running performance and physiological adaptations depending on the training intensity distribution (TID) in an 8-week intervention in endurance athletes. Sixty well-trained male runners (age: 34 ± 6 years, relative ⩒O2peak : 69 ± 3ml kg-1 min-1 ) were recruited and allocated to a pyramidal (PYR), pyramidal + plyometric training (PYR + PLY), polarized (POL), and polarized + plyometric training (POL + PLY) periodization. The periodization patterns were isolated manipulations of TID, while training load was kept constant. Participants were tested pre- and post-intervention for body mass, velocity at 2 and 4 mmol·L-1 of blood lactate concentration (vBLa2, vBLa4), absolute and relative ⩒O2peak and 5-km running time trial performance, counter movement jump and squat jump. There were significant group × time interactions for vBla4 (p=0.0235), CMJ (p=0.0234), SJ (p=0.0168), and 5-km running time trial performance (p=0.0035). Specifically, vBla4 and 5-km running time trial performance showed the largest post-intervention improvements in PYR + PLY (2.4% and 1.6%) and POL + PLY (2.1% and 1.8%), respectively. No significant interactions were observed for body mass, absolute and relative ⩒O2peak , peak heart rate, lactate peak and rating of perceived exertion. In conclusion, an 8-week training periodization seems to be effective in improving performance of well-trained endurance runners. Including plyometric training once a week appeared to be more efficacious in maximizing running performance improvements, independently from the TID adopted.

Type of self-talk matters: Its effects on perceived exertion, cardiorespiratory, and cortisol responses during an iso-metabolic endurance exercise.

Self-talk is an effective mental training technique that has been shown to facilitate or debilitate an athlete's performance, depending on its valence. Although the effects of self-talk have been supported by observing change in sport performance, little is known about how self-talk can induce physiological changes. Specifically, it is important to understand if the type of self-talk (positive, neutral, or negative) and can influence stress-related parameters, such as perceived exertion, cardiorespiratory, and cortisol responses. The study's objective was therefore to investigate the top-down effect of positive and negative self-talk compared to a dissociative activity during an iso-metabolic running exercise on autonomic regulation of cardiorespiratory function. Twenty-nine well-trained male runners [38±13years, 177±7cm and 73±7kg] volunteered to participate in a randomized-group design study that included a negative self-talk (NST), a positive self-talk, and a dissociative group (DG). First, participants underwent an incremental running test on a treadmill to determine the maximal oxygen uptake (V̇O2max ). Next, participants received a mental training session on self-talk and created three positive and three negative self-talk statements. Finally, participants underwent a 60-min steady-state running exercise on a treadmill at 70% of V̇O2max , during which they were cued at 20-, 35-, and 50-min with their personal self-created positive or negative self-talk statements while the DG listened to a documentary. Cardiorespiratory parameters and rate of perceived exertion (RPE) were recorded throughout the 60-min endurance exercise. In addition, salivary cortisol samples were obtained at waking and after treatment. Although oxygen uptake, carbon dioxide production, RPE, and heart rate significantly changed overtime during the 60-min steady-state running exercise, no significant main treatment effect was found. However, RPE scores, minute ventilation, breathing frequency, and salivary cortisol were significantly higher in the NST group compared to the two other groups. These data suggest that NST [emotion-induced stress, as reflected by elevated cortisol] altered the breathing frequency response. In conclusion, manipulating self-talk alters hormonal response patterns, modulates cardiorespiratory function, and influences perceived exertion.

Effects of 16weeks of pyramidal and polarized training intensity distributions in well-trained endurance runners.

The aim of this study was to investigate the effects of four different training periodizations, based on two different training intensity distributions during a 16‐week training block in well‐trained endurance runners. Sixty well‐trained male runners were divided into four groups. Each runner completed one of the following 16‐week training interventions: a pyramidal periodization (PYR); a polarized periodization (POL); a pyramidal periodization followed by a polarized periodization (PYR → POL); and a polarized periodization followed by a pyramidal periodization (POL → PYR). The PYR and POL groups trained with a pyramidal or polarized distribution for 16 weeks. To allow for the change in periodization for the PYR → POL and POL → PYR groups, the 16‐week intervention was split into two 8‐week phases, starting with pyramidal or polarized distribution and then switching to the other. The periodization patterns were isolated manipulations of training intensity distribution, while training load was kept constant. Participants were tested pre‐, mid‐ and post‐intervention for body mass, velocity at 2 and 4 mmol·L−1 of blood lactate concentration (vBLa2, vBLa4), absolute and relative peak oxygen consumption (V˙O2peak) and 5‐km running time trial performance. There were significant group × time interactions for relative V˙O2peak (p < 0.0001), vBLa2 (p < 0.0001) and vBLa4 (p < 0.0001) and 5‐km running time trial performance (p = 0.0001). Specifically, participants in the PYR → POL group showed the largest improvement in all these variables (~3.0% for relative V˙O2peak, ~1.7% for vBLa2, ~1.5% for vBLa4, ~1.5% for 5‐km running time trial performance). No significant interactions were observed for body mass, absolute V˙O2peak, peak heart rate, lactate peak and rating of perceived exertion. Each intervention effectively improved endurance surrogates and performance in well‐trained endurance runners. However, the change from pyramidal to polarized distribution maximized performance improvements, with relative V˙O2peak representing the only physiological correlate.

Steady-state dot{V}{text{O}}_{2} above MLSS: evidence that critical speed better represents maximal metabolic steady state in well-trained runners

The metabolic boundary separating the heavy-intensity and severe-intensity exercise domains is of scientific and practical interest but there is controversy concerning whether the maximal lactate steady state (MLSS) or critical power (synonymous with critical speed, CS) better represents this boundary. We measured the running speeds at MLSS and CS and investigated their ability to discriminate speeds at which dot{V}{text{O}}_{2} was stable over time from speeds at which a steady-state dot{V}{text{O}}_{2} could not be established. Ten well-trained male distance runners completed 9–12 constant-speed treadmill tests, including 3–5 runs of up to 30-min duration for the assessment of MLSS and at least 4 runs performed to the limit of tolerance for assessment of CS. The running speeds at CS and MLSS were significantly different (16.4 ± 1.3 vs. 15.2 ± 0.9 km/h, respectively; P < 0.001). Blood lactate concentration was higher and increased with time at a speed 0.5 km/h higher than MLSS compared to MLSS (P < 0.01); however, pulmonary dot{V}{text{O}}_{2} did not change significantly between 10 and 30 min at either MLSS or MLSS + 0.5 km/h. In contrast, dot{V}{text{O}}_{2} increased significantly over time and reached dot{V}{text{O}}_{2,,max } at end-exercise at a speed ~ 0.4 km/h above CS (P < 0.05) but remained stable at a speed ~ 0.5 km/h below CS. The stability of dot{V}{text{O}}_{2} at a speed exceeding MLSS suggests that MLSS underestimates the maximal metabolic steady state. These results indicate that CS more closely represents the maximal metabolic steady state when the latter is appropriately defined according to the ability to stabilise pulmonary dot{V}{text{O}}_{2}.

Effect of the Depth of Cold Water Immersion on Sleep Architecture and Recovery Among Well-Trained Male Endurance Runners.

Introduction: The aim of the present study was to investigate the effect of the depth of cold water immersion (CWI) (whole-body with head immersed and partial-body CWI) after high-intensity, intermittent running exercise on sleep architecture and recovery kinetics among well-trained runners.Methods: In a randomized, counterbalanced order, 12 well-trained male endurance runners (O2max = 66.0 ± 3.9 ml·min−1·kg−1) performed a simulated trail (≈18:00) on a motorized treadmill followed by CWI (13.3 ± 0.2°C) for 10 min: whole-body immersion including the head (WHOLE; n = 12), partial-body immersion up to the iliac crest (PARTIAL; n = 12), and, finally, an out-of-water control condition (CONT; n = 10). Markers of fatigue and muscle damage—maximal voluntary isometric contraction (MVIC), countermovement jump (CMJ), plasma creatine kinase [CK], and subjective ratings—were recorded until 48 h after the simulated trail. After each condition, nocturnal core body temperature (Tcore) was measured, whereas sleep and heart rate variability were assessed using polysomnography.Results: There was a lower Tcore induced by WHOLE than CONT from the end of immersion to 80 min after the start of immersion (p < 0.05). Slow-wave sleep (SWS) proportion was higher (p < 0.05) during the first 180 min of the night in WHOLE compared with PARTIAL. WHOLE and PARTIAL induced a significant (p < 0.05) decrease in arousal for the duration of the night compared with CONT, while only WHOLE decreased limb movements compared with CONT (p < 0.01) for the duration of the night. Heart rate variability analysis showed a significant reduction (p < 0.05) in RMSSD, low frequency (LF), and high frequency (HF) in WHOLE compared with both PARTIAL and CONT during the first sequence of SWS. No differences between conditions were observed for any markers of fatigue and muscle damage (p > 0.05) throughout the 48-h recovery period.Conclusion: WHOLE reduced arousal and limb movement and enhanced SWS proportion during the first part of the night, which may be particularly useful in the athlete's recovery process after exercise. Future studies are, however, required to assess whether such positive sleep outcomes may result in overall recovery optimization.

Effects of a Short-Term "Fat Adaptation with Carbohydrate Restoration" Diet on Metabolic Responses and Exercise Performance in Well-Trained Runners.

Periodized carbohydrate availability can enhance exercise capacity, but the effects of short-term fat adaptation carbohydrate restoration (FACR) diets on metabolic responses and exercise performance in endurance athletes have not been conclusively determined. This study aimed to investigate the effect of a FACR diet on measures of resting metabolism, exercise metabolism, and exercise performance. Well-trained male runners (n = 8) completed a FACR dietary intervention (five days’ carbohydrate < 20% and fat > 60% energy, plus one-day carbohydrate ≥ 70% energy), and a control high-carbohydrate (HCHO) diet for six days (carbohydrate > 60% energy; fat < 20% energy) in a randomized crossover design. Pre- and post-intervention metabolic measures included resting metabolic rate (RMR), respiratory quotient (RQ), maximum fat oxidation rate during exercise (MFO), and maximum fat oxidation intensity (FATmax). Measures of exercise performance included maximal oxygen uptake (VO2max), running economy (RE), and 5 km running time trial (5 km-TT). In FACR compared with HCHO, there were significant improvements in FATmax (p = 0.006) and RE (p = 0.048). There were no significant differences (p > 0.05) between FACR and HCHO in RMR, RQ, VO2max, or 5 km-TT. Findings suggest that a short-term (six days) FACR diet may facilitate increased fat oxidation and submaximal exercise economy but does not improve 5 km-TT performance.

Effect of Resistance Training of Psoas Major in Combination With Regular Running Training on Performance in Long-Distance Runners.

The study determined whether the increase in the cross-sectional area (CSA) of psoas major, which is known as a hip-flexion muscle, by resistance training combined with running training improves the performance of long-distance runners. Subjects were 8 well-trained male long-distance runners. The personal best time in a 5000-m race was 15:10.0 (0:20.5) (mean [SD]). Each subject performed resistance training twice per week with running training for 12 weeks. The authors used 3 resistance training regimens that would train the hip flexor muscles. Training intensity was a maximum of 10 repetitions. The training amount was 3 sets × 10 times during the first 4 weeks followed by 4 sets × 10 times during the last 8 weeks. The authors measured the CSA of psoas major using magnetic resonance imaging and the performance of long-distance runners using a constant velocity running test before (pre) and after (post) the training term. The combination training significantly (P < .01, d = 0.34) increased the CSA of psoas major (pre: 16.2 [1.5]cm2, post: 16.7 [1.4]cm2) and significantly (P < .01, d = 1.41) improved the duration of the constant velocity running test (pre: 500 [108]s, post: 715 [186]s). Moreover, multiple regression analysis showed that the pre to post change in the duration of the constant velocity exercise was significantly correlated with the change in CSA of the psoas major. The authors suggest that resistance training of psoas major with running training is correlated with an improvement in the performance of long-distance runners.

Running at Increasing Intensities in the Heat Induces Transient Gut Perturbations.

The risk of exercise-induced endotoxemia is increased in the heat and is primarily attributable to changes in gut permeability resulting in the translocation of lipopolysaccharides (LPS) into the circulation. The purpose of this study was to quantify the acute changes in gut permeability and LPS translocation during submaximal continuous and high-intensity interval exercise under heat stress. A total of 12 well-trained male runners (age 37 [7]y, maximal oxygen uptake [VO2max] 61.0 [6.8]mL·min-1·kg-1) undertook 2 treadmill runs of 2 × 15-minutes at 60% and 75% VO2max and up to 8 × 1-minutes at 95% VO2max in HOT (34°C, 68% relative humidity) and COOL (18°C, 57% relative humidity) conditions. Venous blood samples were collected at the baseline, following each running intensity, and 1 hour postexercise. Blood samples were analyzed for markers of intestinal permeability (LPS, LPS binding protein, and intestinal fatty acid-binding protein). The increase in LPS binding protein following each exercise intensity in the HOT condition was 4% (5.3μg·mL-1, 2.4-8.4; mean, 95% confidence interval, P < .001), 32% (4.6μg·mL-1, 1.8-7.4; P = .002), and 30% (3.0μg·mL-1, 0.03-5.9; P = .047) greater than in the COOL condition. LPS was 69% higher than baseline following running at 75% VO2max in the HOT condition (0.2 endotoxin units·mL-1, 0.1-0.4; P = .011). Intestinal fatty acid-binding protein increased 43% (2.1ng·mL-1, 0.1-4.2; P = .04) 1 hour postexercise in HOT compared with the COOL condition. Small increases in LPS concentration during exercise in the heat and subsequent increases in intestinal fatty acid-binding protein and LPS binding protein indicate a capacity to tolerate acute, transient intestinal disturbance in well-trained endurance runners.

A warm-up performed with proper-weight sandbags on the leg improves the speed and RPE performance of 100 m sprint in collegiate male sprinters.

Muscle performance can be notably improved following a preloading maximal or near maximal stimulus due to the induction of postactivation potentiation, but the success of a preloading exercise in generating a postactivation potentiation response depends on the balance between fatigue and potentiation. However, the optimal warm-up strategy for sprint runners before a match may be not well established until now. Fifteen well-trained male sprint runners performed four different warm-up protocols: warm-up with 0% body mass; warm-up with 2% body mass; warm-up with 4% body mass; warm-up with 8% body mass. The weight-bearing sandbag was tied about 3~5 cm above each ankle joint. During the 100-meter test, the time and rating of perceived exertion (RPE) in the first 30 meters, time in the first 60 meters, and time in the 100 meters were recorded, respectively. Two-high-speed digital video cameras were separately set in the sagittal planes on the left side of a line drawn at a distance of 30 m and 60 m from the start line to record the sprint motion. A warm-up performed with a sandbag weighted 4% of body mass could significantly improve the time and the RPE score of 100 m sprint by improving average velocity, stride frequency, average stride length, and average accelerated velocity during the sections of 0~30 m, 30~60 m and 60~100 m. This positive effect was better than that of 2% body-weigh effect. However, a warm-up performed with a sandbag weighted 8% of body mass had no significant influence on the performance of a 100 m sprint. Current results indicated that a warm-up performed with proper-weight(4% body mass) sandbags on the leg was beneficial to the improvement of 100 m sprint performance, and the mechanism might be that it effectively activated the main muscles and neuromuscular regulation of running and produced a better postactivation potentiation.

Acute effect of dynamic stretching or running on endurance running performance in well-trained male runners

Acute effect of dynamic stretching or running on endurance running performance in well-trained male runners

Sports Drink Intake Pattern Affects Exogenous Carbohydrate Oxidation during Running.

This study aimed to determine whether the pattern of carbohydrate sports drink ingestion during prolonged submaximal running affects exogenous carbohydrate oxidation rates and gastrointestinal (GI) comfort. Twelve well-trained male runners (27 ± 7 yr; 67.9 ± 6.7 kg; V˙O2peak, 68 ± 7 mL·kg·min) completed two exercise trials of 100 min steady-state running at 70%V˙O2peak. In each of the trials, 1 L of a 10% dextrose solution, enriched with [U-C] glucose, was consumed as either 200 mL every 20 min (CHO-20) or 50 mL every 5 min (CHO-5). Expired breath and venous blood samples were collected at rest and every 20 min during exercise. Subjective scales of GI comfort were recorded at regular intervals. Average exogenous carbohydrate oxidation rates were 23% higher during exercise in CHO-20 (0.38 ± 0.11 vs 0.31 ± 0.11 g·min; P = 0.017). Peak exogenous carbohydrate oxidation was also higher in CHO-20 (0.68 ± 0.14 g·min vs 0.61 ± 0.14 g·min; P = 0.004). During exercise, total carbohydrate oxidation (CHO-20, 2.15 ± 0.47; CHO-5, 2.23 ± 0.45 g·min, P = 0.412) and endogenous carbohydrate oxidation (CHO-20, 1.78 ± 0.45; CHO-5, 1.92 ± 0.40 g·min; P = 0.148) were not different between trials. Average serum glucose (P = 0.952) and insulin (P = 0.373) concentrations were not different between trials. There were no differences in reported symptoms of GI comfort and stomach bloatedness (P > 0.05), with only 3% of reported scores classed as severe (≥5 out of 10). Ingestion of a larger volume of carbohydrate solution at less frequent intervals during prolonged submaximal running increased exogenous carbohydrate oxidation rates. Neither drinking pattern resulted in increased markers of GI discomfort to a severe level.

The effect of night-time exercise on sleep architecture among well-trained male endurance runners.

The aim of the present study was to investigate the effects of night-time (21:00hours) high-intensity, intermittent exercise on sleep architecture among well-trained athletes in a laboratory setting. In a randomized, counterbalanced order, 11 well-trained male runners completed a simulated trail-running exercise (TRAIL) on a motorized treadmill and a resting condition (REST; no exercise during the day). After each condition, nocturnal autonomic nervous system activity and core body temperature (CBT) were measured and sleep was analysed using polysomnography and actigraphy. Markers of muscle damage (maximal voluntary contraction [MVC], plasma creatine kinase concentration [CK] and perceived muscle soreness) were recorded before and immediately (POST), 24hr (H24) and 48hr (H48) after exercise. TRAIL induced a high level of fatigue and mild exercise-induced muscle damage, as determined by a reduction in MVC (-9.4%, p<.01, d=-1.36) and increases in [CK] (+176.0%, p<.01, d=1.49) and perceived muscle soreness (+4.5 UA, p<.01, d=2.17) compared with REST at H24. A trend for increased non-rapid eye movement (+4.2%; p=.10; d=0.86) and reduced rapid eye movement (-4.4%; p=.07; d=-0.87) during sleep was observed for TRAIL compared with the REST condition. Moreover, compared with REST, TRAIL significantly increased CBT and nocturnal HR during the first part of the night. In conclusion, sleep architecture was modified after night-time, high-intensity exercise among well-trained runners.