Treadmill Running Research Articles

The effect of attentional cues on mechanical efficiency and movement smoothness in running gait: An interdisciplinary investigation

ABSTRACT The aim was to examine the effect of focus of attention cues on foot angle for retraining movement purposes. Twenty (females: 8) rearfoot-striking recreational runners (mass: 72.5 ± 11.8 kg; height: 1.73 ± 0.09 m; age: 32.9 ± 11.3 years) were randomly assigned to an internal focus (IF) (n = 10) or external focus (EF) (n = 10) verbal cue group. Participants performed 5 × 6 minute blocks of treadmill running (control run, 3 × cued running, retention run) at a self-selected running velocity (9.4 ± 1.1 km∙h−1) during a single laboratory visit. Touchdown foot angle, mechanical efficiency, internal and external work were calculated and, centre of mass (COM) and foot movement smoothness was quantified. Linear-mixed effect models showed an interaction for foot angle (p < 0.001, ηp 2 = 0.35) and mechanical efficiency (p < 0.001, ηp 2 = 0.40) when comparing the control to the cued running. Only the IF group reduced foot angle and mechanical efficiency during cued running, but not during the retention run. The IF group produced less external work during the 1st cued run than the control run. COM and foot smoothness were unaffected by cueing. Only an IF produced desired technique changes but at the cost of reduced mechanical efficiency. Movement smoothness was unaffected by cue provision. Changes to foot angle can be achieved within 6 minutes of gait retraining.

Does It Matter? Isometric or Isokinetic Assessment of Quadriceps Strength Symmetry 9 Months After ACLR in Collegiate Athletes.

Greater quadriceps strength symmetry is associated with better outcomes after anterior cruciate ligament reconstruction (ACLR). Isometric and isokinetic assessments of quadriceps strength inform therapeutic exercise prescription and return-to-sport decisions. It is unclear whether isometric and isokinetic measures provide similar information post-ACLR. Quadriceps strength symmetry is similar between isometric and isokinetic assessments. Isokinetic and isometric strength symmetries have similar associations to functional knee kinetics and self-reported knee function. Cross-sectional study. Level 3. NCAA Division I athletes (N = 35), 8.9 ± 2.5 months post-ACLR completed isometric and isokinetic quadriceps strength assessments, countermovement jumps (CMJs), and treadmill running. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC). Agreement between isometric and isokinetic strength symmetry was assessed using Bland-Altman analysis, with associations to functional knee kinetics and IKDC assessed using Pearson correlations and linear regressions. Mean difference in quadriceps strength symmetry between isokinetic and isometric assessments was 1.0% (95% limits of agreement of -25.1% to 23.0%). Functional knee kinetics during running and CMJ were moderately to strongly associated with isometric strength symmetry (r = 0.64-0.80, P < 0.01) and moderately associated with isokinetic strength symmetry (r = 0.41-0.58, P < 0.01). IKDC scores were weakly to moderately associated with isometric (r = 0.39, P = 0.02) and isokinetic (r = 0.49, P < 0.01) strength symmetry. Isokinetic and isometric assessments of quadriceps strength symmetry in collegiate athletes 9 months post-ACLR demonstrated strong agreement. Quadriceps strength symmetry is associated with functional knee kinetic symmetry post-ACLR. Considerable individual variation suggests mode of contraction should be consistent throughout postoperative assessment. Isometric strength symmetry may be a better indicator of functional knee kinetic symmetry, while isokinetic strength symmetry may be associated more closely with patient-reported outcomes.

Accuracy of the Apple Watch Series 4 and Fitbit Versa for Assessing Energy Expenditure and Heart Rate of Wheelchair Users During Treadmill Wheelchair Propulsion: Cross-sectional Study.

The Apple Watch (AW) Series 1 provides energy expenditure (EE) for wheelchair users but was found to be inaccurate with an error of approximately 30%, and the corresponding error for heart rate (HR) provided by the Fitbit Charge 2 was approximately 10% to 20%. Improved accuracy of estimated EE and HR is expected with newer editions of these smart watches (SWs). This study aims to assess the accuracy of the AW Series 4 (wheelchair-specific setting) and the Fitbit Versa (treadmill running mode) for estimating EE and HR during wheelchair propulsion at different intensities. Data from 20 manual wheelchair users (male: n=11, female: n=9; body mass: mean 75, SD 19 kg) and 20 people without a disability (male: n=11, female: n=9; body mass: mean 75, SD 11 kg) were included. Three 4-minute wheelchair propulsion stages at increasing speed were performed on 3 separate test days (0.5%, 2.5%, or 5% incline), while EE and HR were collected by criterion devices and the AW or Fitbit. The mean absolute percentage error (MAPE) was used to indicate the absolute agreement between the criterion device and SWs for EE and HR. Additionally, linear mixed model analyses assessed the effect of exercise intensity, sex, and group on the SW error. Interclass correlation coefficients were used to assess relative agreement between criterion devices and SWs. The AW underestimated EE with MAPEs of 29.2% (SD 22%) in wheelchair users and 30% (SD 12%) in people without a disability. The Fitbit overestimated EE with MAPEs of 73.9% (SD 7%) in wheelchair users and 44.7% (SD 38%) in people without a disability. Both SWs underestimated HR. The device error for EE and HR increased with intensity for both SWs (all comparisons: P<.001), and the only significant difference between groups was found for HR in the AW (-5.27 beats/min for wheelchair users; P=.02). There was a significant effect of sex on the estimation error in EE, with worse accuracy for the AW (-0.69 kcal/min; P<.001) and better accuracy for the Fitbit (-2.08 kcal/min; P<.001) in female participants. For HR, sex differences were found only for the AW, with a smaller error in female participants (5.23 beats/min; P=.02). Interclass correlation coefficients showed poor to moderate relative agreement for both SWs apart from 2 stage-incline combinations (AW: 0.12-0.57 for EE and 0.11-0.86 for HR; Fitbit: 0.06-0.85 for EE and 0.03-0.29 for HR). Neither the AW nor Fitbit were sufficiently accurate for estimating EE or HR during wheelchair propulsion. The AW underestimated EE and the Fitbit overestimated EE, and both SWs underestimated HR. Caution is hence required when using SWs as a tool for training intensity regulation and energy balance or imbalance in wheelchair users.

Impact of treadmill running on distal femoral cartilage thickness: a cross-sectional study of professional athletes and healthy controls

PurposeThis present study aimed to assess the impact of treadmill running on distal femoral cartilage thickness.MethodsProfessional athletes aged 20 to 40 years with a history of treadmill running (minimum 75 min per week for the past three months or more) and age-, sex-, and body mass index (BMI)-matched healthy controls were recruited. Demographics and clinical features of participants were recorded. Athletes were divided into subgroup 1 with less than 12 months of treadmill running and subgroup 2 with 12 months or more of treadmill running. Distal femoral cartilage thicknesses were measured at the midpoints of the right medial condyle (RMC), right intercondylar area (RIA), right lateral condyle (RLC), left medial condyle (LMC), left intercondylar area (LIA), and left lateral condyle (LLC) via ultrasonography.ResultA total of 72 athletes (mean age: 29.6 ± 6.6 years) and 72 controls (mean age: 31.9 ± 6.7 years) were enrolled. Athletes had significantly thinner cartilages in the RLC (2.21 ± 0.38 vs. 2.39 ± 0.31 cm, p = 0.002), LLC (2.28 ± 0.37 vs. 2.46 ± 0.35 cm, p = 0.004), and LMC (2.28 ± 0.42 vs. 2.42 ± 0.36 cm, p = 0.039) compared with the control group. Furthermore, cartilage thickness was significantly thinner in subgroup 2 athletes compared with the control group in the RLC (2.13 ± 0.34 vs. 2.39 ± 0.31 cm, p = 0.001), LLC (2.22 ± 0.31 vs. 2.46 ± 0.35 cm, p = 0.005), and LMC (2.21 ± 0.46 vs. 2.42 ± 0.36 cm, p = 0.027); however, subgroup 1 athletes did not have such differences. There was a weak negative correlation between total months of treadmill running and cartilage thickness in the RLC (r = − 0.0236, p = 0.046) and LLC (r = − 0.0233, p = 0.049). No significant correlation was found between the distal femoral cartilage thickness at different sites and the patients’ demographic features, including age, BMI, speed and incline of treadmill running, and minutes of running per session and week (p > 0.05).ConclusionCompared with healthy controls, professional athletes with a history of long-term high-intensity treadmill running had thinner femoral cartilages. The duration (months) of treadmill running was weakly negatively correlated with distal femoral cartilage thickness. Longitudinal studies with prolonged follow-ups are needed to clarify how treadmill running affects femoral cartilage thickness in athletes.

Exercise-induced changes in myocardial glucose utilization during periods of active cardiac growth

Exercise training can promote physiological cardiac growth, which has been suggested to involve changes in glucose metabolism to facilitate hypertrophy of cardiomyocytes. In this study, we used a dietary, in vivo isotope labeling approach to examine how exercise training influences the metabolic fate of carbon derived from dietary glucose in the heart during acute, active, and established phases of exercise-induced cardiac growth. Male and female FVB/NJ mice were subjected to treadmill running for up to 4 weeks and cardiac growth was assessed by gravimetry. Cardiac metabolic responses to exercise were assessed via in vivo tracing of [13C6]-glucose via mass spectrometry and nuclear magnetic resonance. We found that the half-maximal cardiac growth response was achieved by approximately 1 week of daily exercise training, with near maximal growth observed in male mice with 2 weeks of training; however, female mice were recalcitrant to exercise-induced cardiac growth and required a higher daily intensity of exercise training to achieve significant, albeit modest, increases in cardiac mass. We also found that increases in the energy charge of adenylate and guanylate nucleotide pools precede exercise-induced changes in cardiac size and were associated with higher glucose tracer enrichment in the TCA pool and in amino acids (aspartate, glutamate) sourced by TCA intermediates. Our data also indicate that the activity of collateral biosynthetic pathways of glucose metabolism may not be markedly altered by exercise. Overall, this study provides evidence that metabolic remodeling in the form of heightened energy charge and increased TCA cycle activity and cataplerosis precedes cardiac growth caused by exercise training in male mice.

Evaluating the impact of sportswear with different fabric properties on comfort and physiological response during running

ABSTRACT Comfort is vital in sportswear design. Previous research focused on the thermo-physiological comfort of modal blended fabric by examining its physical and thermal properties, neglecting comprehensive wear trials. This study compared the perceived comfort of two sportswear samples: polyester fabric and modal blended fabric. Ten participants (mean age = 22.4) wore the samples in random order during two trials. Each trial involved 25 min of treadmill running at a self-selected speed in a laboratory with a room temperature of 23.5 ± 1°C and 50% humidity. Heart rate, blood lactate level, skin temperature, perceived exertion, self-reported comfort, sportswear weight change, and fabric properties were recorded. Results showed that the blended fabric offered superior comfort despite the polyester fabric demonstrating better moisture transfer. This suggests that fabric composition and absorbency contribute to comfort and moisture transmission. Future studies should explore fabric structures and their impact on comfort in modal blended fabric using comprehensive human trials.

Effect of Circuit Training on Sleep and Cognition in Collegiates with Poor Sleep Quality

Purpose: The study aimed to investigate the effect of circuit training on sleep and cognition in collegiate with poor sleep quality. Methods: The present study was conducted among 30 subjects having poor sleep quality, who were randomly allocated via lottery method to either a circuit training group or a control group i.e., a treadmill running group. The intervention was given for 3 weeks, with 3 sessions of 30 minutes per week each. Subjects were assessed for poor sleep and cognition at the beginning and end of the 3rd week. Result: 3 weeks of circuit training showed significant improvement in sleep and also in working memory and attention. Conclusion: Insufficient sleep is prevailing among college students. Due of their accessibility and minimal danger, non-pharmacological methods are advised. Given the findings of the present study, dynamic circuit training should be recommended as a practical approach to improve poor sleep and cognition in collegiate students

Muscle Activity and Kinematics During Three Hamstring Strengthening Exercises Compared to Sprinting: A Cross-Sectional Study.

During sprinting, the biceps femoris long head predominantly gets injured, while hamstring strengthening exercises predominantly activate the semitendinosus more effectively. Understanding how joint dominance influences hamstring activity may offer clarity on appropriate exercise selection in strengthening programs. This study compared three hip-dominant hamstring exercises: the rocker, perpetuum mobile fast and slow (PMfast and PMslow) and the Nordic Hamstring exercise (NHE) on their potential to simulate sprint-like activity and kinematics. Muscle activity of the posterior kinetic chain (biceps femoris, semitendinosus, gluteus maximus, and medial gastrocnemius) was measured with surface electromyography (sEMG) during the exercises and treadmill running at 75% of the individual maximal sprint velocity in male athletes. sEMG data were normalized to maximal sprinting. 3D-motion capture was employed to assess hip and knee angles. Eight male athletes were included (age: 24.0 years ± SD 2.9; body mass: 76.8 kg ± 7.7; height: 1.79 m ± 0.08). Greater activity of the hamstrings occurred during the explosive exercises ranging from 63.9% [95%CI: 56.3-71.5%] (rocker) to 49.0% [95%CI: 40.4-57.6%] (PMfast) vs.34.0% [95%CI: 29.1-38.9%] (NHE) to 32.1% [95%CI: 26.9-37.3%] (PMslow). The rocker showed greatest hamstring and gluteus maximus activity. Biceps femoris consistently showed greater activity than the semitendinosus across all exercises in peak (mean difference: 0.16, [95%CI: 0.07-0.26]) and average (mean difference: 0.06, [95%CI: 0.01-0.11]) activity. PMfast, PMslow and NHE demonstrated less hip flexion angle at peak hamstring activity than the rocker and high-speed running and every exercise showed less hamstring elongation stress than during high-speed running. Hamstring activity is comparable to high-intensity treadmill running for NHE and PMslow, and greater for the rocker and PMfast. Gluteus maximus activity varied, with the rocker and PMfast showing greater activity than in sprinting. All examined exercises demonstrated their peak activity at short hamstring muscle length. 3b.

Combined physical training protects the left ventricle from structural and functional damages in experimental pulmonary arterial hypertension

BackgroundUnder the adverse remodeling of the right ventricle and interventricular septum in pulmonary arterial hypertension (PAH) the left ventricle (LV) dynamics is impaired. Despite the benefits of combined aerobic and resistance physical trainings to individuals with PAH, its impact on the LV is not fully understood.ObjectiveTo test whether moderate-intensity combined physical training performed during the development of PAH induced by MCT in rats is beneficial to the LV’s structure and function.MethodsMale Wistar rats were divided into two groups: Sedentary Hypertensive Survival (SHS, n = 7); and Exercise Hypertensive Survival (EHS, n = 7) to test survival. To investigate the effects of combined physical training, another group of rats were divided into three groups: Sedentary Control (SC, n = 7); Sedentary Hypertensive (SH, n = 7); and Exercise Hypertensive (EH, n = 7). PAH was induced through an intraperitoneal injection of MCT (60 mg/kg). Echocardiographic evaluations were conducted on the 22nd day after MCT administration. Animals in the EHS and EH groups participated in a combined physical training program, alternating aerobic (treadmill running: 50 min, 60% maximum running speed) and resistance (ladder climbing: 15 climbs with 1 min interval, 60% maximum carrying load) exercises, one session/day, 5 days/week for approximately 4 weeks.ResultsThe physical training increased survival and tolerance to aerobic (i.e., maximum running speed) and resistance (i.e., maximum carrying load) exertions and prevented reductions in ejection fraction and fractional shortening. In addition, the physical training mitigated oxidative stress (i.e., CAT, SOD and MDA) and inhibited adverse LV remodeling (i.e., Collagen, extracellular matrix, and cell dimensions). Moreover, the physical training preserved the amplitude and velocity of contraction and hindered the reductions in the amplitude and velocity of the intracellular Ca2+ transient in LV single myocytes.ConclusionModerate-intensity combined physical training performed during the development of MCT-induced PAH in rats protects their LV from damages to its structure and function and hence increases their tolerance to physical exertion and prolongs their survival.

Are Gait Patterns during In-Lab Running Representative of Gait Patterns during Real-World Training? An Experimental Study.

Biomechanical assessments of running typically take place inside motion capture laboratories. However, it is unclear whether data from these in-lab gait assessments are representative of gait during real-world running. This study sought to test how well real-world gait patterns are represented by in-lab gait data in two cohorts of runners equipped with consumer-grade wearable sensors measuring speed, step length, vertical oscillation, stance time, and leg stiffness. Cohort 1 (N = 49) completed an in-lab treadmill run plus five real-world runs of self-selected distances on self-selected courses. Cohort 2 (N = 19) completed a 2.4 km outdoor run on a known course plus five real-world runs of self-selected distances on self-selected courses. The degree to which in-lab gait reflected real-world gait was quantified using univariate overlap and multivariate depth overlap statistics, both for all real-world running and for real-world running on flat, straight segments only. When comparing in-lab and real-world data from the same subject, univariate overlap ranged from 65.7% (leg stiffness) to 95.2% (speed). When considering all gait metrics together, only 32.5% of real-world data were well-represented by in-lab data from the same subject. Pooling in-lab gait data across multiple subjects led to greater distributional overlap between in-lab and real-world data (depth overlap 89.3-90.3%) due to the broader variability in gait seen across (as opposed to within) subjects. Stratifying real-world running to only include flat, straight segments did not meaningfully increase the overlap between in-lab and real-world running (changes of <1%). Individual gait patterns during real-world running, as characterized by consumer-grade wearable sensors, are not well-represented by the same runner's in-lab data. Researchers and clinicians should consider "borrowing" information from a pool of many runners to predict individual gait behavior when using biomechanical data to make clinical or sports performance decisions.

Mixed-Method Heat Acclimation Induces Heat Adaptations in International Triathletes Without Training Modification

Abstract Purpose Heat acclimation (HA) kinetics often necessitates that the intervention is conducted in the weeks immediately preceding athletic competitions, potentially interfering with a training taper. Therefore, we investigated the efficacy of a mixed-method HA protocol, superimposed over planned external training loads, during the 3-weeks prior to the 2022 U23 World Triathlon Championships. Methods Six international triathletes completed 8 pre-competition HA sessions (5 active: running/cycling, 3 passive: hot water immersion [HWI]), across 2-weeks. Outdoor high-intensity training sessions were followed by 30–60 min HWI, whilst low-intensity cycling/running sessions were completed in a hot, humid environmental chamber. To assess heat adaptations, participants completed three 25 min heat stress tests (HST) involving iso-speed treadmill running (session 1 = HST1, session 5 = HST2, and session 8 = HST3). Physiological, haematological and wellbeing monitoring were conducted throughout HA. Results Reduced heart rate (~ − 6 beats/min) was observed within HST3 (P = 0.01, ηp2 = 0.64), versus HST1 and HST2. No changes in core temperature were observed across HSTs (P = 0.055,ηp2 = 0.44). Sweat sodium concentration was lower by HST2 at the arm (− 23 ± 16 mmol/L, P = 0.02) and back (− 27 ± 17 mmol/L, P = 0.01). White blood cell count reduced from baseline to the end of HA (P = 0.02, ηp2 = 0.27), but no changes were found in any other haematological markers (all P &gt; 0.05). Perceptual wellbeing measures did not change across HA (all P &gt; 0.05). Conclusion By HST3, seven prior mixed-method HA sessions improved markers of heat adaptation (exercising HR and sweat concentration) within international triathletes. Mixed-method HA may be implemented without modifying training load, with no apparent detrimental effects on athlete health or training stress markers.

[Exercise promotes irisin expression to ameliorate renal injury in type 2 diabetic rats].

To investigate the role of irisin in exercise-induced improvement of renal function in type 2 diabetic rats. Forty male SD rats aged 4-6 weeks were randomized into normal control group, type 2 diabetes mellitus model group, diabetic exercise (DE) group and diabetic irisin (DI) group (n=8). The rats in DE group were trained with treadmill running for 8 weeks, and those in DI group were given scheduled irisin injections for 8 weeks. After the treatments, blood biochemical parameters of the rats were examined, and renal histopathology was observed with HE, Masson and PAS staining. Western blotting was used to detect the protein expression levels in the rats'kidneys. The diabetic rats showed significantly increased levels of fasting insulin, total cholesterol, triglyceride, serum creatinine and blood urea nitrogen with lowered serum irisin level (all P < 0.05). Compared with those in DM group, total cholesterol, triglyceride, serum creatinine and blood urea nitrogen levels were decreased and serum irisin levels were increased in both DE and DI groups (all P < 0.05). The rats in DM group showed obvious structural disorders and collagen fiber deposition in the kidneys, which were significantly improved in DE group and DI group. Both regular exercises and irisin injections significantly ameliorated the reduction of FNDC5, LC3-II/I, Atg7, Beclin-1, p-AMPK, AMPK and SIRT1 protein expressions and lowered of p62 protein expression in the kidneys of the diabetic rats (all P < 0.05). Both exercise and exogenous irisin treatment improve nephropathy in type 2 diabetic rats possibly due to irisin-mediated activation of the AMPK/SIRT1 pathway in the kidneys to promote renal autophagy.

Effects of CurraNZ, a New Zealand Blackcurrant Extract during 1 Hour of Treadmill Running in Female and Male Marathon des Sables Athletes in Hot Conditions: Two Case Studies.

Four weeks before competition in the 2023 Marathon des Sables, a 6-stage, ~250 km running event in the Sahara Desert, we examined the effects of a 7-day intake of New Zealand blackcurrant extract (210 mg anthocyanins per day) on 1 h treadmill running-induced physiological and metabolic responses in the heat (~34 °C, relative humidity: ~30%) in non-acclimatized amateur female and male athletes (age: 23, 38 yrs, BMI: 24.2, 28.4 kg·m-2, body fat%: 29.2, 18.8%, V˙O2max: 50.1, 52.1 mL·kg-1·min-1). During the 1 h run at 50%V˙O2max (speed female: 7.3, male: 7.5 km·h-1), indirect calorimetry was used, and heart rate was recorded at 15 min intervals with core temperature monitoring (0.05 Hz). The 1 h runs took place 3 h after a light breakfast and 2 h after intake of the final dose of New Zealand blackcurrant extract with water allowed ad libitum during the run. The New Zealand blackcurrant extract had no effects on the female athlete. The respiratory exchange ratio (RER) of the female athlete in the non-supplement control condition was 0.77 ± 0.01, indicating an existing ~77% contribution of fat oxidation to the energy requirements. In the male athlete, during 1 h of running, fat oxidation was higher by 21% (p < 0.01), carbohydrate oxidation was 31% lower (p = 0.05), RER was 0.03 units lower (p = 0.04), and core temperature was 0.4 °C lower (p < 0.01) with no differences for heart rate, minute ventilation, oxygen uptake, and carbon dioxide production for the New Zealand blackcurrant condition compared to the non-supplement control condition. Seven-day intake of New Zealand blackcurrant extract (210 mg anthocyanins per day) provided beneficial physiological and metabolic responses during exertional heat stress by 1 h of indoor (~34 °C) treadmill running in a male Marathon des Sables athlete 4 weeks before competition. Future work is required to address whether New Zealand blackcurrant provides a nutritional ergogenic effect for Marathon des Sables athletes during long-duration running in the heat combined with personalized nutrition.

Change in femoral cartilage cross-sectional area after aerobic and resistance exercise.

We compared the immediate response and recovery of femoral cartilage morphology following aerobic or resistance exercise to a control condition. Fifteen healthy young males (23.9 years; 170.1 cm; 69.7 kg) visited the laboratory three separate days and randomly performed one of the 30 min exercise aerobic exercise (treadmill running); resistance exercises (leg presses, back squats, and knee extensions); or seated rest as the control, each followed by the 50 min recovery. Ultrasonographic images of the femoral cartilage cross-sectional area (CSA) were obtained before and after exercise and every 5 min thereafter. To test exercise effects over time, a mixed model analysis of variance and Tukey-Kramer post-hoc tests were performed (p<0.05). The femoral cartilage CSA was different (condition × time: F34,742=4.30, p<0.0001) that the femoral cartilage CSA was decreased after the aerobic (-5.8%, p<0.0001) and the resistance (-3.4%, p=0.04) exercises, compared to the pre-exercise levels. Deformed femoral cartilage CSA took 35- and 10 min to return to the pre-exercise levels after aerobic and resistance exercises (p>0.09), respectively. Thirty minutes of moderate exertion performing aerobic or resistance exercises immediately reduced the femoral cartilage CSA. A rest period ranging from 10 to 35 min was required for cartilage recovery after weight-bearing exercises.

Menstrual Cycle Phase has no Influence on Performance-Determining Variables in Endurance-Trained Athletes: The FENDURA Project.

To investigate the effect of the MC and endogenous sex hormone concentrations on performance-determining variables in three distinct MC phases in endurance-trained females. Twenty-one eumenorrheic trained/highly trained endurance athletes completed a standardized test battery during the early follicular phase (EFP), ovulatory phase (OP), and mid-luteal phase (MLP) for either one (n = 7) or two test cycles (n = 14). MC phases were determined using calendar-based counting, urinary ovulation testing, and verified with serum hormone analysis. MCs were retrospectively classified as eumenorrheic or disturbed. Disturbed MCs were excluded from analysis. The test battery consisted of 4-6 x 5-min submaximal stages with stepwise speed increases, a 30-s all-out double-poling ski ergometer test, and a maximal incremental treadmill running test. At a group level, there was no effect of MC phase or the serum concentrations of estrogen and progesterone on peak oxygen uptake (O2peak), oxygen uptake at 4 mmol·L-1 blood lactate concentration, time-to-exhaustion, running economy, or mean 30-s power output (MPO30s). Serum testosterone concentration was positively associated with MPO30s (p = 0.016). Changes in O2peak from EFP to MLP were inconsistent between individuals and across cycles. None of the measured performance-determining variables were influenced by MC phase or serum estrogen or progesterone concentrations. While some individual patterns could be observed, there was no indication that any single MC phase is consistently associated with improved or impaired O2peak on a group level.

Oxidative phosphorylation in brown adipose tissue in a type II diabetes mellitus mouse model after forced treadmill running

Aim. To study the effect of forced exercises on the content and parameters of oxidative phosphorylation in brown adipose tissue of mice with type II diabetes mellitus.Materials and methods. To model the disease, we used a high-fat diet and physical exercises in the form of forced treadmill running for 4 weeks. The content of oxidative phosphorylation enzymes in brown adipose tissue was determined by Western blotting.Results. Modeling diabetes in experimental animals was accompanied by expansion of adipose tissue. However, in brown adipose tissue, the content of all oxidative phosphorylation components decreases. Apparently, during type II diabetes mellitus modeling in mice, there is a decrease in the “energy efficiency” in brown adipose tissue, which is partially offset by an increase in its content in the body. Regular physical activity in mice with type II diabetes mellitus, in contrast to healthy animals, contributes to a decrease in the content of brown adipose tissue. At the same time, the content of most oxidative phosphorylation components in brown adipose tissue increases, in some casesб it even exceeds the baseline values. The latter is typical of a variable load mode – when the execution time of exercises periodically changes.Conclusion. The obtained results suggest that metabolic rearrangements in brown adipose tissue may serve as some of the mechanisms of preventive and projective effects of physical activity in type 2 diabetes mellitus.

Acute physiological, biomechanical, and perceptual responses of runners wearing downward-curved carbon fiber insoles.

In a randomized controlled cross-over study ten male runners (26.7 ± 4.9 years; recent 5-km time: 18:37 ± 1:07 min:s) performed an incremental treadmill test (ITT) and a 3-km time trial (3-km TT) on a treadmill while wearing either carbon fiber insoles with downwards curvature or insoles made of butyl rubber (control condition) in light road racing shoes (Saucony Fastwitch 9). Oxygen uptake, respiratory exchange ratio, heart rate, blood lactate concentration, stride frequency, stride length and time to exhaustion were assessed during ITT. After ITT, all runners rated their perceived exertion, perceived shoe comfort and perceived shoe performance. Running time, heart rate, blood lactate levels, stride frequency and stride length were recorded during, and shoe comfort and shoe performance after, the 3-km TT. All parameters obtained during or after the ITT did not differ between the two conditions [range: p = 0.188 to 0.948 (alpha value: 0.05); Cohen's d = 0.021 to 0.479] despite the rating of shoe comfort showing better scores for the control insoles (p = 0.001; d = -1.646). All parameters during and after the 3-km TT showed no differences (p = 0.200 to 1.000; d = 0.000 to 0.501) between both conditions except for shoe comfort showing better scores for control insoles (p = 0.017; d = -0.919). Running with carbon fiber insoles with downwards curvature did not change running performance or any submaximal or maximal physiological or biomechanical parameter and perceived exertion compared to control condition. Shoe comfort is impaired while running with carbon fiber insoles. Wearing carbon fiber insoles with downwards curvature during treadmill running is not beneficial when compared to running with control insoles.

Comparison of muscle activity of the lower limbs while running on different treadmill models.

Treadmill running is a common method of exercise and to study human locomotion. Research has examined the kinematics and kinetics of overground and treadmill running, but there has been less focus on the levels of muscle activity during treadmill running. We investigated if muscle activity is different while running overground compared to running on a variety of treadmills. A total of 11 healthy individuals ran at 3 speeds (2.6, 3.6, 4.5 m/s) under 4 different running conditions (3 treadmills, overground). The three treadmills included a typical home exercise treadmill, a midsize commercial research treadmill, and a large, instrumented research treadmill. Surface EMG of the tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF) and biceps femoris (BF) muscles were measured for each running condition. The integrated EMG was computed for each running condition for the stance and swing phase, as well as 100 ms before and after the heel-strike. Friedman analysis revealed significant effects during the stance phase for GM and RF at all speeds, such that muscle activation was lower on the treadmills relative to overground. During the stance phase at faster speeds, the muscle activity was higher for the TA and lower for the BF while running on the different treadmills compared to overground running. Before heel-strike, the TA was significantly less active during treadmill compared to overground running at 2.6 m/s and the RF showed significantly higher activity at 3.6 m/s and 4.5 m/s while running on the different treadmills. Summarizing, differences were mainly observed between the different treadmill conditions relative to overground running. Muscle activation differences between the different treadmill conditions were observed at faster running speeds for RF during the pre-heel-strike phase only. Different types of treadmills with different mechanical properties affects the muscle activity during stance phase as well as in preparation to heel-strike. Additionally, the muscle activity is greater during overground compared to treadmill running during the stance phase for the GM, BF, and RF.

Lactobacillus gasseri BNR17 Ameliorates Dexamethasone-Induced Muscle Loss in BALB/c Mice and C2C12 Myotubes.

This study aimed to investigate the effects and mechanism of Lactobacillus gasseri BNR17, a probiotic strain isolated from human breast milk, on dexamethasone-induced muscle loss in mice and cultured myotubes. BALB/c mice were intraperitoneally injected with dexamethasone, and orally administered L. gasseri BNR17 for 21 days. L. gasseri BNR17 treatment ameliorated dexamethasone-induced decline in muscle function, as evidenced by an increase in forelimb grip strength, treadmill running time, and rotarod retention time in both female and male mice. In addition, L. gasseri BNR17 treatment significantly increased the mass of the gastrocnemius and quadriceps muscles. Dual-energy X-ray absorptiometry showed a significant increase in lean body mass and a decrease in fat mass in both whole body and hind limb after treatment with L. gasseri BNR17. It was found that L. gasseri BNR17 treatment downregulated serum myostatin level and the protein degradation pathway composed of muscle-specific ubiquitin E3 ligases, MuRF1 and MAFbx, and their transcription factor FoxO3. In contrast, L. gasseri BNR17 treatment upregulated serum insulin-like growth factor-1 level and Akt-mTOR-p70S6K signaling pathway involved in protein synthesis in muscle. As a result, L. gasseri BNR17 treatment significantly increased the levels of major muscular proteins such as myosin heavy chain and myoblast determination protein 1. Consistent with in vivo results, L. gasseri BNR17 culture supernatant significantly ameliorated dexamethasone-induced C2C12 myotube atrophy in vitro. In conclusion, L. gasseri BNR17 ameliorates muscle loss by downregulating the protein degradation pathway and upregulating the protein synthesis pathway.

Menthol alleviates post-race elevations in muscle soreness and metabolic and respiratory stress during running.

We evaluated (1) whether participating in middle- and long-distance running races augments muscle soreness, oxygen cost, respiration, and exercise exertion during subsequent running, and (2) if post-race menthol application alleviates these responses in long-distance runners. Eleven long-distance runners completed a 1500-m race on day 1 and a 3000-m race on day 2. On day 3 (post-race day), either a 4% menthol solution (Post-race menthol) or a placebo solution (Post-race placebo) serving as a vehicle control, was applied to their lower leg skin, and their perceptual and physiological responses were evaluated. The identical assessment with the placebo solution was also conducted without race participation (No-race placebo). The integrated muscle soreness index increased in the Post-race placebo compared to the No-race placebo (P < 0.001), but this response was absent in the Post-race menthol (P = 0.058). Oxygen uptake during treadmill running tended to be higher (4.3%) in the Post-race placebo vs. No-race placebo (P = 0.074). Oxygen uptake was 5.4% lower in the Post-race menthol compared to the Post-race placebo (P = 0.018). Minute ventilation during treadmill running was 6.7-7.6% higher in the Post-race placebo compared to No-race placebo, whereas it was 6.6-9.0% lower in the Post-race menthol vs. Post-race placebo (all P ≤ 0.001). The rate of perceived exertion was 7.0% lower in the Post-race menthol vs. Post-race placebo (P = 0.007). Middle- and long-distance races can subsequently elevate muscle soreness and induce respiratory and metabolic stress, but post-race menthol application to the lower legs can mitigate these responses and reduce exercise exertion in long-distance runners.