No abstract

A crucial subject in sports is identifying the inter-individual variation in response to training, which would allow creating individualized pre-training schedules, improving runner's performance. We aimed to analyze heterogeneity in individual responses to two half-marathon training programs differing in running volume and intensity in middleaged recreational women. 20 women (40 ± 7 years, 61 ± 7 kg, 167 ± 6 cm, and VO 2 max = 48 ± 6 mL•kg −1 •min −1) underwent either moderate-intensity continuous (MICT) or high-intensity interval (HIIT) 12-week training. They were evaluated before and after training with maximal incremental tests in the laboratory (VO 2 max) and in the field (time to exhaustion, TTE; short interval series and long run). All the women participated in the same half-marathon and their finishing times were compared with their previous times. Although the improvements in the mean finishing times were not significant, MICT elicited a greater reduction (3 min 50 s, P = 0.298), with more women (70%) improving on their previous times, than HIIT (reduction of 2 min 34 s, P = 0.197, 50% responders). Laboratory tests showed more differences in the HIIT group (P = 0.008), while both groups presented homogeneous significant (P < 0.05) increases in TTE. Both in the short interval series and in the long run, HIIT induced better individual improvements, with a greater percentage of responders compared to MICT (100% vs 50% in the short series and 78% vs 38% in the long run). In conclusion, variability in interindividual responses was observed after both MICT and HIIT, with some participants showing improvements (responders) while others did not (non-responders) in different performance parameters, reinforcing the idea that individualized training prescription is needed to optimize performance.

No abstract

Altitude training has become increasingly popular in recent decades. Its central and peripheral effects are well-described; however, few studies have analyzed the effects of intermittent hypobaric hypoxia (IHH) alone on skeletal muscle morphofunctionality. Here, we studied the effects of IHH on different myofiber morphofunctional parameters, investigating whether contractile activity is required to elicit hypoxia-induced adaptations in trained rats. Eighteen male Sprague-Dawley rats were trained 1 month and then divided into three groups: (1) rats in normobaria (trained normobaric inactive, TNI); (2) rats subjected daily to a 4-h exposure to hypobaric hypoxia equivalent to 4,000 m (trained hypobaric inactive, THI); and (3) rats subjected daily to a 4-h exposure to hypobaric hypoxia just before performing light exercise (trained hypobaric active, THA). After 2 weeks, the tibialis anterior muscle (TA) was excised. Muscle cross-sections were stained for: (1) succinate dehydrogenase to identify oxidative metabolism; (2) myosin-ATPase to identify slow- and fast-twitch fibers; and (3) endothelial-ATPase to stain capillaries. Fibers were classified as slow oxidative (SO), fast oxidative glycolytic (FOG), fast intermediate glycolytic (FIG) or fast glycolytic (FG) and the following parameters were measured: fiber cross-sectional area (FCSA), number of capillaries per fiber (NCF), NCF per 1,000 μm2 of FCSA (CCA), fiber and capillary density (FD and CD), and the ratio between CD and FD (C/F). THI rats did not exhibit significant changes in most of the parameters, while THA animals showed reduced fiber size. Compared to TNI rats, FOG fibers from the lateral/medial fields, as well as FIG and FG fibers from the lateral region, had smaller FCSA in THA rats. Moreover, THA rats had increased NCF in FG fibers from all fields, in medial and posterior FIG fibers and in posterior FOG fibers. All fiber types from the three analyzed regions (except the posterior FG fibers) displayed a significantly increased CCA ratio compared to TNI rats. Global capillarisation was also increased in lateral and medial fields. Our results show that IHH alone does not induce alterations in the TA muscle. The inclusion of exercise immediately after the tested hypoxic conditions is enough to trigger a morphofunctional response that improves muscle capillarisation.

The use of weights when training is very common, especially in compensatory work and in performing supplementary exercises. A new type of weight appeared in the market in 2015 with the name of Powerinstep. It is a weight placed on the instep of athletes running shoes (Padullés & Rius, 2015). The goal of this study was to analyse the effectiveness of the use of these weights (Powerinstep) regarding the effect of biomechanical and certain athletic performance variables on two everyday runners groups with similar training methods. The sample used was composed of 19 subjects (9 male and 10 female). The control group (without weight) was made up of 4 subjects and the experimental group had 15 subjects (4 had 50-gram weights on each foot, 5 had 100 grams on each foot, and 6 had 150 grams on each foot). The weight given to each athlete depended on their body weight. There was a pre-test and a post-test done to each athlete with a training period of 14 weeks in between. These tests were: the Bosco test (SJ, CMJ, and ABK) and the Léger test (UMTT). The analysed variables were: height (cm) in SJ, CMJ, and ABK; time (s) in the Léger test; maximum and average heart rate (bpm); contact, flight, and passing times (s) of both left and right feet; step length (m) both left and right feet; stride length (m); the elevation of the centre of mass (cm) during left and right steps and the strides. Both the experimental group and the control group trained under the same time and schedule conditions, with the same work volume, and used the same training system. The only thing that varied between the groups was the whether they used weights or not. Given the sample characteristics, the statistical analysis method was non-parametric (Wilcoxon test). A comparative analysis of the variations between the pre-test and the post-test was done, both in the intergroups (control vs. experimental) and the intragroups (between the 3 subgroups of the experimental group). The differences found in the variations of the control group were not statistically significant (p<0.05). Neither were they in comparing the variations of the intragroups between the subgroups of 50g, 100g, and 150g weights (p<0.05). With this, it can be deduced that the weights given to each athlete regarding their body weight were correct. Statistically significant differences were found in the variations of the experimental group regarding the length of the stride (p=0.05), increasing this one, as well as the length of the left step (p=0.04). However, it has to be taken into account that the length of the step can be considered an improvement, but only if it is regulated to fit each athlete's ideal step length in relation to their trochanteric length, and if it is also associated with an increase of their driving force. Likewise, given the limitations of the sample for significant changes to be given over time, tendencies of the changes in the average percentages were analysed. Even if they did not offer statistically significant differences, they did offer results to tak...