This study aimed to estimate the effect of the coronavirus disease 2019 (COVID-19) quarantine on low back pain (LBP) intensity, prevalence, and associated risk factors among adults in Riyadh (Saudi Arabia). A total of 463 adults (259 males and 204 females) aged between 18 and 64 years and residing in Riyadh (Saudi Arabia) participated in this cross-sectional study. A self-administered structured questionnaire composed of 20 questions regarding demographic characteristics, work- and academic-related aspects, physical activity (PA), daily habits and tasks, and pain-related aspects was used. The LBP point prevalence before the quarantine was 38.8%, and 43.8% after the quarantine. The LBP intensity significantly increased during the quarantine. The low back was also the most common musculoskeletal pain area. Furthermore, during the quarantine, a significantly higher LBP intensity was reported by those individuals who (a) were aged between 35 and 49 years old, (b) had a body mass index equal to or exceeding 30, (c) underwent higher levels of stress, (d) did not comply with the ergonomic recommendations, (e) were sitting for long periods, (f) did not practice enough physical activity (PA), and (g) underwent teleworking or distance learning. No significant differences were found between genders. The COVID-19 quarantine resulted in a significant increase in LBP intensity, point prevalence, and most associated risk factors.

Regular exercise improves health, modulating the immune system and impacting inflammatory status. Immunoglobulin G (IgG) N-glycosylation reflects changes in inflammatory status; thus, we investigated the impact of regular exercise on overall inflammatory status by monitoring IgG N-glycosylation in a previously inactive, middle-aged, overweight and obese population (50.30 ± 9.23 years, BMI 30.57 ± 4.81). Study participants (N = 397) underwent one of three different exercise programs lasting three months with blood samples collected at baseline and at the end of intervention. After chromatographically profiling IgG N-glycans, linear mixed models with age and sex adjustment were used to investigate exercise effects on IgG glycosylation. Exercise intervention induced significant changes in IgG N-glycome composition. We observed an increase in agalactosylated, monogalctosylated, asialylated and core-fucosylated N-glycans (padj = 1.00 × 10⁻⁴, 2.41 × 10⁻²⁵, 1.51 × 10⁻²¹ and 3.38 × 10⁻³⁰, respectively) and a decrease in digalactosylated, mono- and di-sialylated N-glycans (padj = 4.93 × 10⁻¹², 7.61 × 10⁻⁹ and 1.09 × 10⁻²⁸, respectively). We also observed a significant increase in GP9 (glycan structure FA2[3]G1, β = 0.126, padj = 2.05 × 10⁻¹⁶), previously reported to have a protective cardiovascular role in women, highlighting the importance of regular exercise for cardiovascular health. Other alterations in IgG N-glycosylation reflect an increased pro-inflammatory IgG potential, expected in a previously inactive and overweight population, where metabolic remodeling is in the early stages due to exercise introduction.

The aim of this study was to determine whether the dynamic motor stereotype of movement (shooting technique) is violated under conditions of an increased lactate concentration in a player’s blood after a 30–15 intermittent fitness test. The hypotheses was that there would be statistically significant differences in ball speed and shooting accuracy in jump shots on the goal before and after the occurrence of fatigue in the player. The sample of respondents consisted of 10 top-level handball players of the highest competition rank in Croatia. The results showed significant differences before and after the fatigue protocol in the run-up speed (F = 5.66; p = 0.02), in the maximum speed of the forearm (F = 5.85; p = 0.02) and the hand (F = 4.01; p = 0.04), in the speed in the shoulder joint (F = 5.39; p = 0.02) and wrist joint (F = 4.06; p = 0.04), and in the ball shooting speed (F = 5.42; p = 0.02). The accuracy of the shot was, on average, lower (36.20 vs. 33.17 cm) but not significantly so. High blood lactate levels affect changes in certain kinematic parameters during the performance of a jump shot in handball. Consequently, this reduces the speed of the shot, which can affect situational performance as one of the two significant parameters of scoring success.

The main aim of this research is to analyse the kinematic model of two different variations of executing the jump shot, one performed after one step in the preparation phase and the other performed after a three-step preparation phase (run-up). Respondents (N = 27) are female Croatian national handball team players (U17 and U19). After basic anthropometric and morphological measurements, along with the warmup, respondents proceeded to shoot with one- and three-step shots directed at targets in the upper and lower opposite corner of the goal. A significant difference was found in all measured kinematic parameters between one- and three-step jump shots: hand velocity (p < 0.001 for the upper opposite (UO) and p < 0.001 for the lower opposite target (LO)); hand height reached (p < 0.05 UO and p < 0.01 LO); jump height (p < 0.001 UO and p < 0.001 LO); shoulder velocity (p < 0.001 UO and p < 0.001 LO); and ball velocity (p < 0.05 UO and p < 0.01 LO). Coaches should incorporate specific jump shots after one step to automate this movement and produce the best shooting technique, which will allow them to have smaller differences or no differences between techniques with three-steps and one-step jump shots. Consequently, this will lead to better performance indicators which consist of shooting on target from various positions in the field.

Fat mass and fat-free mass have become useful clinical indices in determining healthy growth and physical development during critical periods of childhood and adolescence; however, despite a wide range of nutritional surveillance its study is limited by a lack of reference data. The purpose of this study was to establish sex-specific and age-specific standards for fat mass and fat-free mass in a large sample of Croatian children and adolescents. In this cross-sectional study, we collected data from 12,678 participants aged 11 to 18 years old (mean age ± standard deviation (SD): 14.17 ± 2.25 years; height 164.56 ± 11.31 cm; weight: 57.45 ± 13.73 kg; body mass index: 21.24 ± 3.67 kg/m²; 53% girls). Fat mass and fat-free mass were measured three times by bioelectrical impedance. The Lambda, Mu and Sigma methods were used to create percentile charts for fat mass index (FMI) and fat-free mass index (FFMI; fat mass and fat-free mass divided by height²). Sex and age differences were calculated using an analysis of variance (ANOVA) with post hoc comparisons. Boys had lower FMI (from 2.66 to 3.89) and higher FFMI values (from 16.90 to 17.80) in all age groups, compared to girls (for FMI from 2.79 to 5.17 and for FFMI from 14.50 to 14.90, p < 0.001). In boys, FMI slightly declined until the age of 14, after which an increase from the age of 15 to 18 was observed. In girls, FMI gradually increased from the age of 11 to 18 (p < 0.001). In general, FFMI increased by age in boys [F(7,5440) = 52.674, p < 0.001], while girls had more stable FFMI across all age groups [F(7,7222) = 2.728, p = 0.057]. The newly established sex-specific and age-specific reference data could be used for national surveillance and to screen for children and adolescents with high FMI and low FFMI.

The SwingVision (SV) application represents software for the automatic analysis of movement and specific parameters in tennis, but no study evaluated its applicability so far. Therefore, the aim of this research is to determine the validity of SwingVision for monitoring speed and placement parameters when performing serve and the frequency, type, and rotation of each stroke in the game. The sample of participants (N = 5) consisted of elite male junior tennis players (mean age 15.6 ± 0.35 years, mean height 179.16 ± 5.71 cm, and mean weight 72.62 ± 3.89 kg). Video analyses of closed and open character exercises were used to compare real data and those obtained using SV. The placement results determined good and very good validity (ICC = 0.83–0.87). In terms of speed, the results were found to have good validity (Speed_AD-ICC = 0.76–0.80). SV provided very good validity (ICC = 0.97) in the stroke detection parameter and also presented good validity in recognizing the rotation of shots (ICC = 0.76). SV provides valid objective feedback on tennis performance. Thus, the results justify the use of SV as a helpful tool in the training process, both in training and matches.