Effect of specific endurance on the physical responses of young athletes during soccer small-sided games

This study aimed to compare the physical responses of soccer players with different levels of specific endurance during SSG performed by teams balanced according to athletes’ specific endurance. Eighteen U-17 athletes from a team that participated in national competitions took part in this study. The Yo-Yo Intermittent Recovery Test Level 2 (YIRT2) was used to measure the athletes’ specific endurance. Then, athletes were allocated to two groups balanced according to their positional status and YIRT2 scores: in Group1 players with the highest results in the YIRT2 and in Group 2 with the lower YIRT2 scores. Athletes played two four-minute bouts of 3vs.3 small-sided games with goalkeepers with four minutes of passive rest. Total distance covered, average speed, and accelerations were obtained by GPS devices carried by each player. Group 1 presented higher total distance covered (large effect size), higher average speed (large effect size), and higher total distance covered in accelerations above 1 m·s-2 (moderate effect size), compared to Group 2. We concluded that specific endurance can partially influence physical responses of young soccer athletes during small-sided games. This information is important to appropriately prescribe small-sided games during the training process, possibly by grouping together athletes with similar specific endurance and, therefore, promoting an adequate stimulus to better-conditioned athletes.

Monetary Policy Strategies for a Low-Rate Environment

In low-rate environments, policy strategies that involve holding rates “lower for longer” (L4L) may mitigate the effects of the effective lower bound (ELB). However, these strategies work in part by managing the public's expectations, which is not always realistic. Using the Fed's large-scale macroeconometric model, we study the effectiveness of L4L policies when financial market participants are forward-looking but other agents are not. We find that the resulting limited ability to manage expectations reduces but does not eliminate the advantages of L4L policies. The best policies provide adequate stimulus at the ELB while avoiding sizable overshoots of inflation and output.

Oxygen consumption and heart rate obtained in a ramp protocol are equivalent during exercise session of rectangular loading at ventilatory thresholds for athletes

Training near or at ventilatory threshold (VT) is an adequate stimulus to improve the thresholds for sedentary subjects, but a higher intensity is necessary for conditioned subjects. The choice of cardiopulmonary exercise testing (CPx) protocol has an influence on VTs identification and can reduce their reliability for exercise prescription. This study tested if VO2 and heart rate (HR) corresponding to first (VT1) and second ventilatory threshold (VT2) determined during a ramp protocol were equivalent to those observed in rectangular load exercises at the same intensity in runners elite athletes (EA) and non-athletes (NA). Eighteen health subjects were divided into two groups: EA (n = 9, VO2max 68.6 mL·kg-1·min-1) and NA (n = 9, VO2max 47.2 mL·kg-1·min-1). They performed CPx and 48h and 96h later, a continuous running lasting 1 h for VT1 and until exhaustion for VT2. The results showed that EA at VT1 session, presented delta differences for VO2 (+9.1%, p = 0.125) vs. NA (+20.5%, p = 0.012). The Bland-Altman plots for VT1 presented biases of (4.4 ± 6.9) and (5.5 ± 5.6 mLO2·kg-1·min-1) for AE and NA, respectively. In VT2, the VO2 and HR of the NA showed biases of (0.4 ± 2.9 mLO2·kg-1·min-1) and (4.9 ± 4.2 bpm). The ramp protocol used in this study was inappropriate for NA because it underestimates the values of VO2 and HR at VT1 found in the rectangular load exercise. The HR showed good agreement at VT2 with CPx and may be a good parameter for controlling exercise intensity.

VO2 at Maximal and Supramaximal Intensities: Lessons to High-Intensity Interval Training in Swimming

Purpose:To establish appropriate work intensity for interval training that would elicit maximal oxygen uptake (VO2max) for well-trained swimmers.Methods:Twelve male competitive swimmers completed an incremental protocol to determine the minimum velocity at VO2max (νVO2max) and, in randomized order, 3 square-wave exercises from rest to 95%, 100%, and 105% of νVO2max. Temporal aspects of the VO2 response were examined in these latter.Results:Swimming at 105% of νVO2max took less (P < .04) absolute time to achieve 90%, 95%, and 100% of VO2max intensities (35.0 ± 7.7, 58.3 ± 15.9, 58.3 ± 19.3 s) compared with 95% (72.1 ± 34.3, 106.7 ± 43.9, 151.1 ± 52.4 s) and 100% (55.8 ± 24.5, 84.2 ± 35.4, 95.6 ± 29.8 s) of VO2max. However, swimming at 95% of νVO2max resulted in longer absolute time (P < .001) at or above the desired intensities (90%: 268.3 ± 72.5 s; 95%: 233.8 ± 74.3 s; 100%: 173.6 ± 78.2 s) and more relative time at or above 95% of VO2max than 105% of νVO2max (68.6% ± 13.5% vs 55.3% ± 11.5%, P < .03), and at or above 100% of VO2max than 100% and 105% of νVO2max (52.7% ± 16.3% vs 28.2% ± 10.5% and 34.0% ± 11.3%, P < .001). At 60 s of effort, swimmers achieved 85.8% ± 11.2%, 88.3% ± 5.9%, and 94.7% ± 5.5% of the VO2max when swimming at 95%, 100%, and 105% of νVO2max, respectively.Conclusions:When training to elicit VO2max, using higher swimming intensities will promote a faster VO2 response but a shorter time spent above these intensities. However, lower intensities allow maintaining the desired response for a longer period of time. Moreover, using the 60-s time period seem to be a more adequate stimulus than shorter ones (~30-s), especially when performed at 105% of νVO2max intensity.

Physical Activity in Adolescent with Mental Retardation: Is Adapted Basketball Training Adequate Stimulus to Improve Cardiorespiratory Fitness and Sport Skills Performance?

Summary The purpose of the study was to examine the effects of an adapted basketball training program on the cardiorespiratory fitness and sport skills performance of adolescents with mental retardation (MR). Fifty adolescents with mild MR who participated in this study were divided in two groups. Experimental group (n = 25; mean ± SD age: 15.7 ± 0.9 years) performed the adapted training program, four times per week during eight weeks. A control group (n = 25; mean ± SD age: 15.9 ± 0.8 years) followed ordinary physical education classes and continued with their normal lifestyle. Exercise testing included the six-minute walk test (6MWT), monitoring of heart rate frequency and sport skills performance test battery. Results showed a significant difference between groups pre- and post-treatment in 6MWT distance. The experimental group experienced a 10% increase in covered distance pre- to post-testing (p < 0.05), whereas controls had no significant changes in the same period. Conducted adapted training also resulted in significant improvement in examined sport skills performance. However, this kind and duration of experimental procedure did not result in significant differences in anthropometric variables and heart rate frequency. This study demonstrated that adapted basketball training is an adequate stimulus for improvement in cardiorespiratory fitness and sport skills performance of adolescents with mild MR. The advantage of this type of adaptive training program is that it does not require a large financial input, but only the engagement of a qualified and dedicated physical education professor.