BACKGROUND: Lower limb muscular asymmetry is not well studied and may have a negative impact on performance. OBJECTIVE: To estimate how muscular strength and strength asymmetry affect jumping performance in soccer players. METHODS: Twenty-eight male professional soccer players took part in the study. The countermovement jump (CMJ) without arm swing was used to determine jumping height. Muscle strength was measured concentrically at 60 and 300[Formula: see text]/s. RESULTS: The peak moment of the knee extensors was positively and significantly correlated with the CMJ; [Formula: see text] 0.608 at 300[Formula: see text]/s and [Formula: see text] 0.489 at 60[Formula: see text]/s. The asymmetry of the knee flexors between the stronger and weaker leg was negatively and moderately correlated with the CMJ at 300[Formula: see text]/s ([Formula: see text]0.396). The regression model ([Formula: see text] 0.474) showed that an increase of 0.18-Nm/kg in the relative strength of the knee extensors at 300[Formula: see text]/s (by one SD) was related to an increase of 3-cm in the CMJ. Reducing the asymmetry of the knee flexors by 6.8 percentage points (by one SD) was related to a rise of 1.7-cm in the CMJ. CONCLUSIONS: Greater strength in the knee extensors, preferably tested at higher velocity, and reduced asymmetry in the strength of the lower hamstring muscles have a statistically significant effect on the CMJ.

BACKGROUND: The effects of contemporary cryo-compression devices on function are limited compared to traditional applications of cooling. Development of cooling protocols are warranted. OBJECTIVE: To investigate the effects of three different cryo-compressive modalities applied at the knee on the isokinetic strength of the quadriceps over a re-warming period. METHODS: Eleven healthy male participants took part (23 [Formula: see text] 14 years; 78.3 [Formula: see text] 14.5 Kg; 180 [Formula: see text] 9.5 cm) randomly assigned to receive all modalities (Game Ready[Formula: see text] (GR), Swellaway[Formula: see text] (SA), Wetted Ice (WI)) applied for 15-min, separated by 1-week. Skin surface temperature (T[Formula: see text]) via thermography and the concentric peak moment (PM) of the quadriceps at 60 and 180[Formula: see text]/s were collected pre-, immediately-post and at 20-min post-intervention. RESULTS: Significant reductions occurred in T[Formula: see text] across all timepoints for all modalities ([Formula: see text] 0.05). Significant reductions in PM for WI were noted across all timepoints and PM for GR and SA immediately-post ([Formula: see text] 0.05) only. CONCLUSION: Precaution for immediately returning to sport following cryotherapy is required and influenced by type of cooling on muscle strength responses. Alternate targeted treatment modalities to minimise deferred deleterious effects on muscle strength may be considered. Research into length of application, periodisation and location is warranted for the development of such contemporary cryo-compressive modalities in applied practice.

BACKGROUND: Isokinetic evaluation is considered the gold standard in muscle strength measurement due to its sensitivity, intra-dynamometer reproducibility and usefulness in the injury prevention screening and follow up of subjects with musculoskeletal pathologies, neurological disease or after surgical operation. However, can one switch among different isokinetic dynamometers for the purpose of knee muscles evaluation? OBJECTIVES: To comprehensively evaluate the compatibility of the isokinetic short concentric and eccentric strength evaluation protocol and of the fatigability resistance evaluation between three different isokinetic devices. METHODS: Eighteen recreationally active men underwent three isokinetic knee testing sessions on three different isokinetic devices with 7–10 days of rest between each session. Relative (Pearson’s r product-moment correlation coefficient – PCC) and absolute (standard error of measurement – SEM, Cohen effect sizes (d) and probabilistic inferences – MBI) parameters of reproducibility were determined to assess the inter-dynamometer agreement. RESULTS: For the short concentric and eccentric strength evaluation protocol, the extensors in concentric mode and the flexors in eccentric mode can be compared (eventually with transposition formulas provided) between Biodex, Con-Trex and Cybex (almost all PCC [Formula: see text] 0.80). The DCR could be compared between Con-Trex and Cybex and between Biodex and Cybex pairs (eventually with transposition formula provided). For the fatigability resistance evaluation protocol, the total sum can be compared for extensors (eventually with transposition formulas provided) for PM for all dynamometer pairs considered and, in the case of MW, only for Biodex and Con-Trex (PCC [Formula: see text] 0.80). CONCLUSIONS: Only some of the parameters derived either from the short concentric and eccentric strength evaluation protocol or the fatigability resistance evaluation protocol may be interchangeable providing transposition formulas are applied. Otherwise, isokinetic findings are largely system-dependent save some specific instances.

BACKGROUND: The inability of athletes to train or the decrease in the intensity and frequency of training may cause athletes to lose performance. Particularly in view of the current COVID-19 pandemic, maintaining strength outside the normal framework provides an advantage to athletes for the next competitions. OBJECTIVE: To compare the CrossFit Barbara which can be applied easily at home during the off-season or some situations such as the epidemic limitation to classic resistance training methods used to maintain the strength performance of national kickboxers. METHODS: Forty-three national kickboxers, CrossFit (CF, [Formula: see text] 22), and resistance training (RT, [Formula: see text] 21), participated in this study. While CF performed 20 pull-ups, 30 push-ups, 40 sit-ups, and 50 squat exercises, RT performed bench press, lat pull down, leg press, biceps curl, and triceps extension exercises twice per week for six weeks. Before and after the six weeks, the following variables were measured; body mass (BM) and body fat percentage (FP), VO[Formula: see text], bench press (BP), squat (SQ), leg strength (LS), hand grip strength (HGS), pull-up, push-up and counter movement jump (CMJ). RESULTS: BP ([Formula: see text] 0.001, [Formula: see text] 41.125, [Formula: see text] 0.501), SQ ([Formula: see text] 0.001, [Formula: see text] 26.604, [Formula: see text] 0.394), LS ([Formula: see text] 0.001, [Formula: see text] 15.234, [Formula: see text] 0.271), push-up ([Formula: see text] 0.001, [Formula: see text] 31.978, [Formula: see text] 0.438) and pull-up ([Formula: see text] 0.001, [Formula: see text] 24.410, [Formula: see text] 0.373) values changed significantly in group-time interaction between CF and RT groups, while there was no significant difference for the BM ([Formula: see text] 0.198, [Formula: see text] 1.715, [Formula: see text] 0.040), Fat ([Formula: see text] 0.265, [Formula: see text] 1.279, [Formula: see text] 0.030), HGS ([Formula: see text] 0.665, [Formula: see text] 0.190, [Formula: see text] 0.005, CMJ ([Formula: see text] 0.054, [Formula: see text] 3.946, [Formula: see text] 0.088) and VO[Formula: see text] ([Formula: see text]0.747, [Formula: see text] 0.106, [Formula: see text] 0.003). Furthermore, according to the before and after study values, BP, SQ, LS, and CMJ decreased significantly ([Formula: see text] 0.05) while BM, FP, HGS, VO[Formula: see text], pull-up and push-up variables did not in the CF ([Formula: see text] 0.05). In the RT, the pull-up and push-up variables decreased significantly ([Formula: see text] 0.05) while there was no significant difference for BP, SQ, LS, HGS, VO[Formula: see text], body mass, body fat percentage and CMJ ([Formula: see text] 0.05). CONCLUSION: CF Barbara workout was more effective in maintaining strength endurance performances, and RT in maintaining maximum strength performances. According to the individual performance needs of athletes, reasonable training method can be used to prevent performance decrement in the strength domain.

BACKGROUND: The 20-maximum trampoline jump test is a commonly used performance measure in competitive trampoline gymnastics. However, its reliability and characteristics are poorly understood. OBJECTIVE: To determine the reliability of the 20-maximum trampoline jump test and describe its characteristics. METHODS: Thirty-two national and international level trampoline gymnasts (18 [Formula: see text] 5 years) performed two, 20-maximal straight jump tests, separated by 24–72 hours. Time of flight (total, jumps 1–10 and jumps 11–20), force (average and peak), horizontal displacement and contact time were measured by a competition standard system. Test-retest reliability was assessed using intraclass correlation coefficient (ICC), typical error, and coefficient of variation (CV). RESULTS: Total time of flight significantly decreased between trial 1 (31.80 [Formula: see text] 1.98 s) and trial 2 (31.43 [Formula: see text] 1.99 s; [Formula: see text] 0.05), however test-retest reliability was excellent (ICC [Formula: see text] 0.96, CV [Formula: see text] 1.3%). Other time of flight and force measures significantly decreased from trial 1 to trial 2, whereas contact time increased. All secondary measures displayed very high ICC (0.95–0.99) and low CV values (0.5–1.9%), except horizontal displacement (ICC [Formula: see text] 0.54, CV [Formula: see text] 20.6%). CONCLUSION: The 20-maximum test possesses excellent reliability for the assessment of trampoline performance in a wide population of national and international level gymnasts.

BACKGROUND: Whole-body electromyostimulation (WB-EMS) is a new tendency in training used to complement conventional training. OBJECTIVE: The aim was to analyze the effects of training with WB-EMS on body composition, strength and balance in middle-aged women. METHODS: Twenty-eight women were randomly assigned to two groups: the WB-EMS group (age [Formula: see text] 48.1 [Formula: see text] 4.3 years) or the control group (CG) (age [Formula: see text] 51.1 [Formula: see text] 5.4 years). All participants continued their training of 2 days[Formula: see text]week[Formula: see text] and 60 min[Formula: see text]day[Formula: see text] of endurance-dynamic strength exercises and additionally did 20 minutes more of dynamic strength exercises one day[Formula: see text]week[Formula: see text]: the WB-EMS group did the additional training with WB-EMS and the CG did the same training but without WB-EMS. Body composition, muscle isokinetic strength of the knee flexors/extensors and postural stability were measured before and after 8 weeks of training. RESULTS: After the training program, the WB-EMS group showed lower values for the waist circumference (83.00 [Formula: see text] 7.37 vs. 78.50 [Formula: see text] 7.30 cm; [Formula: see text] 0.01), hip circumference (104.80 [Formula: see text] 8.61 vs. 101.00 [Formula: see text] 6.78 cm; [Formula: see text] 0.05) and total fat mass (37.04 [Formula: see text] 6.08 vs. 36.26 [Formula: see text] 5.78%; [Formula: see text] 0.05). In balance stability the WB-EMS group reduced their Fall Risk Index (1.70 [Formula: see text] 0.51 vs. 1.30 [Formula: see text] 0.38 AU; [Formula: see text] 0.01) and deviation (1.50 [Formula: see text] 0.43 vs. 1.03 [Formula: see text] 0.74 AU; [Formula: see text] 0.01) after training and showed lower values in the Fall Risk Index ([Formula: see text] 0.007) and deviation ([Formula: see text] 0.024). CONCLUSIONS: The WB-EMS training program helps reduce the risk of falling and improves body composition variables and balance results in middle-aged physically active women.

We report a longitudinal survey of a 53-year-old man suffering from right knee osteoarthritis who has undergone total knee replacement (TKR). We aimed at evaluating the effect of a short preoperative isokinetic strengthening program on the functional status, pain, and quadriceps and hamstrings strength before and after TKR. The patient performed a 4-week (6 sessions) preoperative isokinetic strengthening program of the quadriceps and hamstrings. The findings for the concentric strength at 60[Formula: see text]/s, 6-minute walk test (6MWT), and Knee injury and Osteoarthritis Outcome Score (KOOS) were recorded. At baseline the patient presented with an overall KOOS score of 44%, a 6MWT of 444 m, a 63% and 21% strength deficits of the quadriceps and hamstrings, respectively. Following the strengthening program, the quadriceps strength of the operated limb improved ([Formula: see text]121 Nm; [Formula: see text]83%), but the function as reflected by the KOOS score remained unchanged. Following the TKR, the concentric isokinetic strength of the quadriceps reappeared altered (63% of deficit) despite pain and functional improvements. This case report underlines the importance of functional evaluation rather than the maximal strength to assess the effectiveness of TKR. However, further studies are necessary to conceptualize the meaning of maximal strength measurement and the impact of associated deficits, if any.

Reliability refers to the consistency of one outcome when the measurement is repeated. Sport scientists are aware of the importance of reliability and, consequently, a large number of single-center studies (performed in only one research center following specific protocols) have been conducted to evaluate the reliability of different testing procedures. Although single-center reliability studies are valuable, their findings could be compromised by the generally low sample size that can be gathered and restricted to the specific population and testing procedures used, reducing external validity. More robust information about the reliability of fitness tests could be obtained by pooling the data collected in independent research centers on a collaborative basis (multicenter reliability studies). This manuscript highlights the potential benefits of multicenter reliability studies and provides a number of recommendations for conducting multicenter reliability studies based on both a priori (researchers from different centers agree to collect data to address a specific question) and a posteriori (the data of published single-center studies are post-hoc combined) approaches.

BACKGROUND: Adolescence is characterized by a rapid and erratic growth period. Many factors completely change in growth period up to 20 years of age, with a very slight alteration during the later years of life. Bioelectric impedance analyzers (BIA) are used in estimating the total and segmental body composition compartments. OBJECTIVE: To determine the validity of different BIAs for young male athletes. METHODS: Sixty-one young male athletes (basketball, football, handball, swimming, and skiing) participated in the study. The validity of Tanita 401A (TANITA), Jawon Segmental Body Composition Analysers model AVIS 333 Plus (AVIS), and Biodynamics Model 310e (BIODYNAMICS) was tested by Bland & Altman analysis and heteroscedasticity, providing the gold standard criterion method, hydrostatic weighing (HW) for body density (D[Formula: see text]), body fat percentage (%BF), and lean body mass (LBM). RESULTS: BIA models used for predicting body composition, except for %BF of TANITA, are valid and in accord with HW for young male athletes. TANITA had significantly lower %BF (5.75 [Formula: see text] 2.95%) and higher LBM (62.12 [Formula: see text] 7.53 kg), compared to HW (10.79 [Formula: see text] 4.17 %BF and 58.80 [Formula: see text] 7.38 kg LBM). Percent BF of BIODYNAMICS and AVIS results were significantly higher (2.04% and 3.3% respectively) than %BF of HW. CONCLUSION: Prediction of body composition compartments of young male athletes using BIA models is valid except for %BF by TANITA. LBM values of HW and BIA models can be used interchangeably. However, these BIA softwares do not have specific options concerning athletic status for the growing age and sex group to clarify population specificity in adolescent male athletes. Therefore, using the same BIA model is recommendable in following up training regimen and nutritional status, in order to avoid underestimating or overestimating the body composition compartments.

BACKGROUND: Small-sided games are a popular training method that have shown its effectiveness in improving athletic performance in football players. OBJECTIVE: To compare the acute physiological and neuromuscular responses and time-motion characteristics during small-sided games played with and without wildcard players. METHODS: Sixteen amateur male football players completed two small-sided games protocol: 4-a-side and 4-a-side with wildcard players. Time-motion characteristics during games, muscular performance parameters before and after small-sided games protocols, physiological response in terms of heart rate and muscle oximetry and rate of perceived exertion were collected. RESULTS: Both small-sided games formats induced changes in sprint performance (before-after comparison), in the rate of perceived exertion, heart rate-related variables and time-motion parameters (p< 0.05). In a comparison between small-sided games formats, lower values of oxygen saturation, heart rate, rate of perceived exertion and time-motion parameters (p< 0.05) were reported during small-sided games with wildcard players in both working and recovery periods. CONCLUSIONS: The inclusion of wildcard players during small-sided games cause a reduction in perceptual, physiological demands and time-motion parameters when compared to control condition.