Gaspare Pavei

Aerobic Fitness Affects the Exercise Performance Responses to Nitrate Supplementation.

PURPOSE Dietary nitrate supplementation has been shown to reduce O2 cost of submaximal exercise, improve exercise tolerance, and enhance performance in moderately trained individuals. In contrast, data have been provided that elite athletes do not benefit from nitrate supplementation. The aim of this study was to evaluate the effects of short-term nitrate supplementation on endurance performance in subjects with different levels of aerobic fitness. METHODS Twenty-one subjects (mean age, 22.7 ± 1.8 yr) with different aerobic fitness level (V˙O2peak value ranging from 28.2 to 81.7 mL·kg·min) participated in a crossover double-blind placebo-controlled study. Subjects were tested after 6 d of supplementation with either 0.5 l per day of nitrate (5.5 mmol)-containing water (NITR) or nitrate-free water (PLA). Participants performed an incremental running test until exhaustion and four repetitions of 6-min submaximal (approximately 80% of gas exchange threshold) constant load exercise on a motorized treadmill. Moreover, subjects performed a 3-km running time trial on the field. RESULTS After NITR, a negative correlation between reduction of O2 cost of submaximal exercise and individual aerobic fitness level was observed (r = 0.80; P < 0.0001). A significant inverse correlation was also found between aerobic fitness level and improvement in performance for 3-km time trial after NITR (r = 0.76; P < 0.0001). Additionally, subjects responded differently to dietary nitrate supplementation according to aerobic fitness level with higher-fit subjects showing a lower increase in plasma [NO3] (r = 0.86; P < 0.0001) and [NO2] (r = 0.75; P < 0.0001). CONCLUSIONS The results of the present study suggest that the individual aerobic fitness level affects the ergogenic benefits induced by dietary nitrate supplementation. The optimal nitrate loading regimen required to elevate plasma [NO2] and to enhance performance in elite athletes is different from that of low-fit subjects and requires further studies.

The biomechanics of race walking: Literature overview and new insights

Abstract This review aims to provide both researchers and coaches with a comprehensive overview of race walking biomechanics and to point out new viable route for future analyses. The examined literature has been divided into three categories according to the method of analysis: kinematics, ground reaction forces and joint power/efficiency. From an overall view, race walking athletes seem to adhere to the ‘straightened knee’ rule, but at race speed they do not observe the ‘no-flight time’ rule. The coach-oriented analysis highlights that stride length (SL) is more important than stride frequency (SF) for increasing speed and it is mainly obtained by ankle and hip joint power. Moreover, kinematic differences (SF, SL and flight time) between male and female athletes were shown. Also, we found that the maximal speed prediction according to dynamic similarity theory with walking (Froude number) is not applicable as the 3D trajectory of the body centre of mass does not follow an arc of circumference as in walking. The analysed literature shows some shortcomings: (1) the data collection is often unreliable because of the mixture of gender and performance level and (2) the analysis has sometimes been performed on a limited number of strides and speeds. These limitations lead to a scattered and incomplete gait description and a biased application of the results. The research strategy adopted so far is promising but further rigorous analyses need to be approached to obtain a fully comprehensive picture of race walking and to provide coaches with consistent results and reference values.

Training Effects on ROS Production Determined by Electron Paramagnetic Resonance in Master Swimmers

Acute exercise induces an increase in Reactive Oxygen Species (ROS) production dependent on exercise intensity with highest ROS amount generated by strenuous exercise. However, chronic repetition of exercise, that is, exercise training, may reduce exercise-induced oxidative stress. Aim of this study was to evaluate the effects of 6-weeks high-intensity discontinuous training (HIDT), characterized by repeated variations of intensity and changes of redox potential, on ROS production and antioxidant capacity in sixteen master swimmers. Time course changes of ROS generation were assessed by Electron Paramagnetic Resonance in capillary blood by a microinvasive approach. An incremental arm-ergometer exercise (IE) until exhaustion was carried out at both before (PRE) and after (POST) training (Trg) period. A significant (P < 0.01) increase of ROS production from REST to the END of IE in PRE Trg (2.82 ± 0.66 versus 3.28 ± 0.66 µmol·min−1) was observed. HIDT increased peak oxygen consumption (36.1 ± 4.3 versus 40.6 ± 5.7 mL·kg−1·min−1 PRE and POST Trg, resp.) and the antioxidant capacity (+13%) while it significantly decreased the ROS production both at REST (−20%) and after IE (−25%). The observed link between ROS production, adaptive antioxidant defense mechanisms, and peak oxygen consumption provides new insight into the correlation between ROS response pathways and muscle metabolic function.

Effects of a Short-Term High-Nitrate Diet on Exercise Performance

It has been reported that nitrate supplementation can improve exercise performance. Most of the studies have used either beetroot juice or sodium nitrate as a supplement; there is lack of data on the potential ergogenic benefits of an increased dietary nitrate intake from a diet based on fruits and vegetables. Our aim was to assess whether a high-nitrate diet increases nitric oxide bioavailability and to evaluate the effects of this nutritional intervention on exercise performance. Seven healthy male subjects participated in a randomized cross-over study. They were tested before and after 6 days of a high (HND) or control (CD) nitrate diet (~8.2 mmol∙day−1 or ~2.9 mmol∙day−1, respectively). Plasma nitrate and nitrite concentrations were significantly higher in HND (127 ± 64 µM and 350 ± 120 nM, respectively) compared to CD (23 ± 10 µM and 240 ± 100 nM, respectively). In HND (vs. CD) were observed: (a) a significant reduction of oxygen consumption during moderate-intensity constant work-rate cycling exercise (1.178 ± 0.141 vs. 1.269 ± 0.136 L·min−1); (b) a significantly higher total muscle work during fatiguing, intermittent sub-maximal isometric knee extension (357.3 ± 176.1 vs. 253.6 ± 149.0 Nm·s·kg−1); (c) an improved performance in Repeated Sprint Ability test. These findings suggest that a high-nitrate diet could be a feasible and effective strategy to improve exercise performance.

Hopping locomotion at different gravity: metabolism and mechanics in humans

Previous literature on the effects of low gravity on the mechanics and energetics of human locomotion already dealt with walking, running, and skipping. The aim of the present study is to obtain a comprehensive view on that subject by including measurements of human hopping in simulated low gravity, a gait often adopted in many Apollo Missions and documented in NASA footage. Six subjects hopped at different speeds at terrestrial, Martian, and Lunar gravity on a treadmill while oxygen consumption and 3D body kinematic were sampled. Results clearly indicate that hopping is too metabolically expensive to be a sustainable locomotion on Earth but, similarly to skipping (and running), its economy greatly (more than ×10) increases at lower gravity. On the Moon, the metabolic cost of hopping becomes even lower than that of walking, skipping, and running, but the general finding is that gaits with very different economy on Earth share almost the same economy on the Moon. The mechanical reasons for such a decrease in cost are discussed in the paper. The present data, together with previous findings, will allow also to predict the aerobic traverse range/duration of astronauts when getting far from their base station on low gravity planets.

Can coordination variability identify performance factors and skill level in competitive sport? The case of race walking

Background Marginal changes in the execution of competitive sports movements can represent a significant change for performance success. However, such differences may emerge only at certain execution intensities and are not easily detectable through conventional biomechanical techniques. This study aimed to investigate if and how competition standard and progression speed affect race walking kinematics from both a conventional and a coordination variability perspective. Methods Fifteen experienced athletes divided into three groups (elite, international, and national) were studied while race walking on a treadmill at two different speeds (12.0 and 15.5 km/h). Basic gait parameters, the angular displacement of the pelvis and lower limbs, and the variability in continuous relative phase between six different joint couplings were analyzed. Results Most of the spatio-temporal, kinematic, and coordination variability measures proved sensitive to the change in speed. Conversely, non-linear dynamics measures highlighted differences between athletes of different competition standard when conventional analytical tools were not able to discriminate between different skill levels. Continuous relative phase variability was higher for national level athletes than international and elite in two couplings (pelvis obliquity—hip flex/extension and pelvis rotation—ankle dorsi/plantarflexion) and gait phases (early stance for the first coupling, propulsive phase for the second) that are deemed fundamental for correct technique and performance. Conclusion Measures of coordination variability showed to be a more sensitive tool for the fine detection of skill-dependent factors in competitive race walking, and showed good potential for being integrated in the assessment and monitoring of sports motor abilities.

Effects of Manipulating Volume and Intensity Training in Masters Swimmers

PURPOSE Recently, some studies have suggested that overall training intensity may be more important than training volume for improving swimming performance. However, those studies focused on very young subjects, and/or the difference between high-volume and high-intensity training was blurred. The aim of this study was to investigate in masters swimmers the effects of manipulation of training volume and intensity on performance and physiological variables. METHODS A group of 10 male masters swimmers (age 32.3 ± 5.1 y) performed 2 different 6-wk training periods followed by 1 wk of tapering. The first period was characterized by high training volume performed at low intensity (HvLi), whereas the second period was characterized by low training volume performed at high intensity (LvHi). Peak oxygen consumption (VO2peak) during incremental arm exercise, individual anaerobic threshold (IAT), and 100-m, 400-m, and 2000-m-freestyle time were evaluated before and at the end of both training periods. RESULTS HvLi training significant increased VO2peak (11.9% ± 4.9% [mean change ± 90%CL], P = .002) and performance in the 400-m (-2.8% ± 1.8%, P = .002) and 2000-m (-3.4% ± 2.9%, P = .025), with a likely change in IAT (4.9% ± 4.7%, P > .05). After LvHi training, speed at IAT (12.4% ± 5.3%, P = .004) and 100-m performance (-1.2% ± 0.8%, P = .001) also improved, without any significant changes in VO2peak, 2000-m, and 400-m. CONCLUSIONS These findings indicate that in masters swimmers an increase of training volume may lead to an improvement of VO2peak and middle- to long-distance performance. However, a subsequent period of LvHi training maintains previous adjustments and positively affects anaerobic threshold and short-distance performance.

Physiological and perceptual responses to nordic walking in a natural mountain environment

Background: Interest around Nordic Walking (NW) has increased in recent years. However, direct comparisons of NW with normal walking (W), particularly in ecologically valid environments is lacking. The aim of our study was to compare NW and W, over long distances in a natural mountain environment. Methods: Twenty one subjects (13 male/8 female, aged 41 ± 12 years, body mass index BMI 24.1 ± 3.7), walked three distinct uphill paths (length 2.2/3.4/7 km) with (NW) or without (W) walking poles over two separate days. Heart rate (HR), energy expenditure (EE), step length (SL), walking speed (WS), total steps number (SN) and rating of perceived exertion (RPE) were monitored. Results: HR (+18%) and EE (+20%) were higher in NW than in W whilst RPE was similar. SN (−12%) was lower and SL (+15%) longer in NW. WS was higher (1.64 vs. 1.53 m s−1) in NW. Conclusions: Our data confirm that, similarly to previous laboratory studies, differences in a range of walking variables are present between NW and W when performed in a natural environment. NW appears to increase EE compared to W, despite a similar RPE. Thus, NW could be a useful as aerobic training modality for weight control and cardiorespiratory fitness.

On the Estimation Accuracy of the 3D Body Center of Mass Trajectory during Human Locomotion: Inverse vs. Forward Dynamics

The dynamics of body center of mass (BCoM) 3D trajectory during locomotion is crucial to the mechanical understanding of the different gaits. Forward Dynamics (FD) obtains BCoM motion from ground reaction forces while Inverse Dynamics (ID) estimates BCoM position and speed from motion capture of body segments. These two techniques are widely used by the literature on the estimation of BCoM. Despite the specific pros and cons of both methods, FD is less biased and considered as the golden standard, while ID estimates strongly depend on the segmental model adopted to schematically represent the moving body. In these experiments a single subject walked, ran, (uni- and bi-laterally) skipped, and race-walked at a wide range of speeds on a treadmill with force sensors underneath. In all conditions a simultaneous motion capture (8 cameras, 36 markers) took place. 3D BCoM trajectories computed according to five marker set models of ID have been compared to the one obtained by FD on the same (about 2,700) strides. Such a comparison aims to check the validity of the investigated models to capture the “true” dynamics of gaits in terms of distance between paths, mechanical external work and energy recovery. Results allow to conclude that: (1) among gaits, race walking is the most critical in being described by ID, (2) among the investigated segmental models, those capturing the motion of four limbs and trunk more closely reproduce the subtle temporal and spatial changes of BCoM trajectory within the strides of most gaits, (3) FD-ID discrepancy in external work is speed dependent within a gait in the most unsuccessful models, and (4) the internal work is not affected by the difference in BCoM estimates.

Different Training Modalities Improve Energy Cost and Performance in Master Runners

Purpose: The aim of this study was to compare the effects of continuous moderate-intensity and discontinuous high-intensity training on running performance in master runners. Methods: Thirty-four male master runners (47.2 ± 7.4 years) were assigned to three different groups: continuous moderate-intensity training (CMIT), discontinuous high-intensity training (DHIT), and control group (CON). CMIT and DHIT performed 8-week of supervised training (3 session·wk−1; ~35 km·wk−1) while CON maintained their normal training habits (3–4 session·wk−1; ~50 km·wk−1). Peak oxygen consumption (V˙O2peak) and peak running speed (vpeak) during incremental treadmill exercise, gas exchange threshold (GET), speed at GET, energy cost of running (Cr), and 5-km performance were evaluated before and after training. Results: Following the training period, both CMIT and DHIT significantly reduced Cr (−4.4 and −4.9%, respectively, P < 0.05), increased speed at GET (3.4 and 5.7%, P < 0.05) and improved 5-km time-trial performance (3.1 and 2.2%, P < 0.05) whereas no differences were found for V˙O2peak and GET (as %V˙O2peak). After training, vpeak improved only for DHIT (6%, P < 0.05). No differences were found in any variable for CON. Conclusions: This study indicates that both CMIT and DHIT may positively affect running performance in middle-aged master runners. This improvement was achieved despite a significant reduction of the amount of weekly training volume.