Effect Of Post-Activation Potentiation By Combining Heavy Squats And Sprints On The Countermovement Long Jump (Pilot Study)

Weightlifting heavy load exercises are commonly used as a key instrument for enhancing performance when compared to those not using the exercise stimulating muscle tone. Studies examined the post-activation effect (PAP) using only one parameter but not in consecutive and intermingling exercises that prolongated the time of the PAP effect duration and maintain increased performance. Nine male students, with resistance training experience, performed warm-up and ‘exercises enhancing muscle tone’ (EEMT) using squats to 90° flexion in the knee joint with 80 % 1 RM (repetition maximum) in 3 sets with 3 repetitions of squat in each set (2-3 min. rest intervals). After EEMT they performed a 10m sprint test in the 2nd and 5th min followed by a countermovement long jump (CLJ) test in the 5th and 6th minute, a 10-m sprint test in the 10th and 11th minute and the CLJ test in the 12th and 14th minute. The results showed that the average improvement was in the 10m sprint after EEMT 0,013 ± 0,05 seconds, but there were no statistical differences observed between the result without and with EEMT (p>0.05). We observed a significant improvement between jumps without and with EEMT in 5 – 14th min (p0.05). It was found that 10m sprint had no negative effect on performance in the long jump and could be regularly applied to prolong the PAP effect

Short-term effects of half-squat jump potentiating protocol on power output and countermovement jump performance

The purpose of this study was to determine short-term effect of complex training with inclusion of postactivation potentiation (PAP) on average power output (Pmax) and countermovement jump (CMJ) in competitive athletes. Sixteen athletes (age: 21.3±3.3 years, height: 178.9 ± 8.6 cm, weight: 74.8±9.9 kg) were pair-matched and randomly assigned into intervention (INT) (n=8), and control group (CON) (n=8). Over a training period of a 6-weeks with training frequency 2 days per week, the subjects underwent pre-, mid- (after 3 weeks), and post-testing (after 6 weeks) in CMJ and Pmax. Before the start of each training session EXP performed PAP protocol which consisted of 3 sets and 4 repetitions of half-squat jump exercise with individualized loads on (Pmax), whereas CON continued their normal complex training without the inclusion of PAP. Both groups significantly improved performance after 6 weeks of training. Novel findings of this study have shown that the INT which has been regularly performing PAP protocol before each training session achieved greater gains in Pmax (16.5 % vs. 4.9 %, p<0.01, from pre- to mid-training) and CMJ (15.4 % vs. 8.3 %, p<0.05, from pre- to post-training) compared to the CON. In conclusion, it seems that performing potentiating protocols before complex training sessions can potentially enhance motor performance in competitive athletes

Numerical models and experiment of air flow in a simulation box for optical wireless communications

In this article, the authors focused on real measurements of mechanical turbulence generated by ventilators in the simulation box for Optical Wireless Communications. The mechanical turbulences disturb the optical beam that propagates along the central axis of the simulation box. The aim of authors is to show the effect of mechanical turbulence on optical beams at different heights in the simulation box. In the Ansys Fluent, we created numerical models which were then compared with real measurements. Authors compared the real and numerical models according to statistical methods

Numerical models and experiment of air flow in a simulation box for optical wireless communications

In this article, the authors focused on real measurements of mechanical turbulence generated by ventilators in the simulation box for Optical Wireless Communications. The mechanical turbulences disturb the optical beam that propagates along the central axis of the simulation box. The aim of authors is to show the effect of mechanical turbulence on optical beams at different heights in the simulation box. In the Ansys Fluent, we created numerical models which were then compared with real measurements. Authors compared the real and numerical models according to statistical methods

Morphological, molecular and hormonal adaptations to early morning versus afternoon resistance training

It has been clearly established that maximal force and power is lower in the morning compared to noon or afternoon hours. This morning neuromuscular deficit can be diminished by regularly training in the morning hours. However, there is limited and contradictory information upon hypertrophic adaptations to time-of-day-specific resistance training. Moreover, no cellular or molecular mechanisms related to muscle hypertrophy adaptation have been studied with this respect. Therefore, the present study examined effects of the time-of-day-specific resistance training on muscle hypertrophy, phosphorylation of selected proteins, hormonal concentrations and neuromuscular performance. Twenty five previously untrained males were randomly divided into a morning group (n = 11, age 23 ± 2 yrs), afternoon group (n = 7, 24 ± 4 yrs) and control group (n = 7, 24 ± 3 yrs). Both the morning and afternoon group underwent hypertrophy-type of resistance training with 22 training sessions over an 11-week period performed between 07:30–08:30 h and 16:00–17:00 h, respectively. Isometric MVC was tested before and immediately after an acute loading exclusively during their training times before and after the training period. Before acute loadings, resting blood samples were drawn and analysed for plasma testosterone and cortisol. At each testing occasion, muscle biopsies from m. vastus lateralis were obtained before and 60 min after the acute loading. Muscle specimens were analysed for muscle fibre cross-sectional areas (CSA) and for phosphorylated p70S6K, rpS6, p38MAPK, Erk1/2, and eEF2. In addition, the right quadriceps femoris was scanned with MRI before and after the training period. The control group underwent the same testing, except for MRI, between 11:00 h and 13:00 h but did not train. Voluntary muscle strength increased significantly in both the morning and afternoon training group by 16.9% and 15.2 %, respectively. Also muscle hypertrophy occurred by 8.8% and 11.9% (MRI, p < 0.001) and at muscle fibre CSA level by 21% and 18% (p < 0.01) in the morning and afternoon group, respectively. No significant changes were found in controls within these parameters. Both pre- and post-training acute loadings induced a significant (p < 0.001) reduction in muscle strength in all groups, not affected by time of day or training. The post-loading phosphorylation of p70S6Thr421/Ser424 increased independent of the time of day in the pre-training condition, whereas it was significantly increased in the morning group only after the training period (p < 0.05). Phosphorylation of rpS6 and p38MAPK increased acutely both before and after training in a time-of-day independent manner (p < 0.05 at all occasions). Phosphorylation of p70S6Thr389, eEF2 and Erk1/2 did not change at any time point. No statistically significant correlations were found between changes in muscle fibre CSA, MRI and cell signalling data. Resting testosterone was not statistically different among groups at any time point. Resting cortisol declined significantly from pre- to post-training in all three groups (p < 0.05). In conclusion, similar levels of muscle strength and hypertrophy could be achieved regardless of time of the day in previously untrained men. However, at the level of skeletal muscle signalling, the extent of adaptation in some parameters may be time of day dependent.peerReviewe