Relationships between training load, peak height velocity, muscle soreness and fatigue status in elite-level young soccer players: a competition season study

Which training load indicators are greater correlated with maturation and wellness variables in elite U14 soccer players?

BACKGROUND

Monitoring of training load is done to improve physical performance and minimize the incidence of injuries. The study examined the correlation between accumulated training load parameters based on periods with maturity (i.e., maturity offset and peak height velocity -PHV- and wellness variables -e.g., stress and sleep quality-). The second aim was to analyze the multi-linear regression between the above indicators.

METHODS

Twenty elite young U14 soccer players (M = 13.26 ± 0.52 years, 95% CI [13.02, 13.51]) were evaluated over 26 weeks (early, mid, and end-season) to obtain stress, sleep quality, and measures of workload in the season (accumulated acute workload [AW], accumulated chronic workload [CW], accumulated acute: chronic workload ratio [ACWLR], accumulated training monotony [TM], accumulated training strain [TS]).

RESULTS

The analysis revealed a moderate, statistically significant negative correlation between sleep quality and training monotony (r = -0.461, p < 0.05). No significant correlations were observed between other variables (p > 0.05). In the multi-linear regression analysis, maturity, PHV, sleep, and stress collectively accounted for variances of 17% in AW, 17.1% in CW, 11% in ACWLR, 21.3% in TM, and 22.6% in TS. However, individual regression coefficients for these predictors were not statistically significant (p > 0.05), indicating limited predictive power.

CONCLUSION

The study highlights the impact of sleep quality on training monotony, underscoring the importance of managing training load to mitigate the risks of overtraining. The non-significant regression coefficients suggest the complexity of predicting training outcomes based on the assessed variables. These insights emphasize the need for a holistic approach in training load management and athlete wellness monitoring.

Validity and reliability of a repeated multi-changes of direction agility test in senior soccer players

Background

This study aimed to evaluate the validity, reliability, and sensitivity of repeated multi-changes of direction agility test (rMCOD) compared to a soccer-specific field test of repeated sprint ability (S-RSA) and repeated sprint ability test (RSA).

Methods

Thirty-five healthy male soccer players (age: 18.4 ± 1.3 years) from Tunisan national soccer league (elite and sub-elite) took part in this study. They performed the tests in a randomized order over five sessions interspaced by at least 72 h. The construct, predictive and discriminant validity, relative and absolute reliability, and sensitivity of the tests were analyzed. The total and best time of the test (the sum for all trials and the trial with the lowest duration on nine, six, and seven attempts for rMCOD, RSA, and S-RSA, respectively), fatigue index, rating of perceived exertion (RPE), and lactate concentration were recorded.

Results

rMCOD correlated with both, S-RSA and RSA in total time (r = 0.85 and r = 0.52, respectively) and fatigue index (r = 0.74 and r = 0.83, respectively). Receiver operator characteristics were not able to discriminate between group levels (elite and sub-elite). When comparing training levels, only the fatigue index in S-RSA showed a difference between groups. Fatigue index, total time, and the best time in rMCOD showed excellent reliability, as well as the minimal change detectable (MCD = 0.89, MCD = 0.63, and MCD = 0.11, respectively) was higher than the standard error of the mean (SEM = 0.32, SEM = 0.23, and 0.04, respectively).

Conclusion

rMCOD showed large to very large predictive validity compared with the S-RSA and RSA, being a reliable test for the following parameters: the best time and total time to perform the test. Nevertheless, this study design cannot ensure whether or not this test is able to detect real changes in performance in response to training since it did not include a training intervention; besides, rMCOD could not distinguish between elite and sub-elite players, which is a limitation.

Different effects of four rest periods after the last weekly training session on young male professional soccer players' physical performance

The main aim of this study was to analyze the optimal pre-competitive recovery period for young male professional soccer players to be in the best conditions to achieve a higher physical performance. Seventeen young male professional soccer players (age: 20.7 ± 1.0 years) who participated in the Tunisian soccer league participated in this study. Players underwent a fitness test battery after four different recovery periods: 12, 24, 36, and 48h following their last training session. The battery fitness test included a linear sprint test (i.e., 5 and 20m distances), squat jumps (SJ), countermovement jumps (CMJ), ball shooting test, a Yo-yo endurance intermittent test (YYIRT-1) and a 15-m ball dribbling agility test (Ag). The main findings indicated that the 12h recovery period resulted in better performance in the 5m sprint test compared to 36h, as well as in the SJs and CMJs as compared to the 48h recovery period. Additionally, the 24h recovery period showed significantly better results in the 20-m sprint test compared to all other recovery periods, as well as in the SJ and Ag tests compared to the 48h recovery period. In practical terms, these findings suggest that coaches should consider scheduling the last training session for soccer players 12-24h before the match to enhance their physical performance, particularly in linear sprinting, vertical jumps, and agility variables. However, in situations where it is not possible to adjust the timing of the last training session, an alternative approach is to incorporate "priming-day" exercises on the match day, around 6-8h prior to the competition.

Training Load and Current Soreness Predict Future Delayed Onset Muscle Soreness in Collegiate Female Soccer Athletes

Background

Delayed onset muscles soreness (DOMS) is an indication of muscle stress and trauma that develops from excessive musculoskeletal loads. Musculoskeletal loads can be measured with wearable devices, but there is limited research on specific training load metrics that most correlate with DOMS after activity.

Purpose

To determine the predictive capabilities of training load variables on the development of lower extremity DOMS in female collegiate soccer athletes throughout an entire season.

Study Design

Prospective Cohort.

Methods

Twenty-seven collegiate female soccer athletes reported their lower extremity DOMS each day prior to all soccer activity. Participants wore Polar heart rate and global positioning monitors to capture training load measures. Pearson correlation coefficients were used to assess the relationships between the training load variables and change in DOMS when collapsed across dates. Separate linear mixed models were performed with the following day's DOMS as the outcome variable, training load and the current day's DOMS as predictor variables, and participants serving as random intercepts.

Results

All training load variables significantly predicted change in DOMS, with number of decelerations (ρ=0.72, p <0.001), minutes spent at greater than 80% of maximum heart rate (HRmax) (ρ=0.71 , p <0.001), and distance (ρ=0.70 , p <0.001) best correlating with change in DOMS. Linear mixed models revealed a significant interaction of all training load and current day's DOMS on the following day's DOMS (p<0.001), but number of decelerations, HRmax, and total number of accelerations demonstrated the highest coefficient of determination (R2 marginal=33.2% - 29.2% , R2 conditional= 46.9% - 44.8%).

Conclusions

Training load variables paired with the current day's DOMS significantly predict lower extremity DOMS in the future, with number of decelerations, accelerations, and HRmax best predicting future DOMS. Although this demonstrates that training load variables predict lower extremity DOMS, future research should incorporate objective measures of strength or jump kinetics to identify if similar relationships exist.

Level of Evidence

Level 3.

Effects of Nutrition Interventions on Athletic Performance in Soccer Players: A Systematic Review

BACKGROUND

More than 270 million participants and 128,893 professional players play soccer. Although UEFA recommendations for nutrition in elite football exist, implementing these guidelines among professional and semiprofessional soccer players remains suboptimal, emphasizing the need for targeted and individualized nutritional strategies to improve adherence to established recommendations.

METHODS

We conducted a comprehensive search in PubMed, Scopus, Web of Science, and clinical trial registers. Inclusion criteria focused on professional or semiprofessional soccer players, nutrition or diet interventions, performance improvement outcomes, and randomized clinical trial study types. We assessed quality using the Risk of Bias 2 (RoB 2) tool. We identified 16 eligible articles involving 310 participants. No nutritional interventions during the recovery period effectively improved recovery. However, several performance-based interventions showed positive effects, such as tart cherry supplementation, raw pistachio nut kernels, bicarbonate and mineral ingestion, creatine supplementation, betaine consumption, symbiotic supplements, and a high-carbohydrate diet. These interventions influenced various aspects of soccer performance, including endurance, speed, agility, strength, power, explosiveness, and anaerobic capacity.

CONCLUSIONS

Specific strategies, such as solutions with bicarbonate and minerals, high carbohydrate diets, and supplements like creatine, betaine, and tart cherry, can enhance the performance of professional soccer players. These targeted nutritional interventions may help optimize performance and provide the competitive edge required in professional soccer. We did not find any dietary interventions that could enhance recovery.

Association between 2D:4D ratios and sprinting, change of direction ability, aerobic fitness, and cumulative workloads in elite youth soccer players

BACKGROUND

The aim of this study was two-fold: (i) to determine the correlation between 2D:4D, maximal oxygen uptake (VO_2max), body fat percentage (BF%), maximum heart rate (HRmax), change of direction (COD), and accumulated acute and chronic workload variables; (ii) to verify if the length of the second digit divided by fourth digit (2D:4D) can explain fitness variables and accumulated training load.

METHODS

Twenty elite young football players (age: 13.26 ± 0.19 years; height: 165.8 ± 11.67 cm; body mass: 50.70 ± 7.56 kg; VO_2max, 48.22 ± 2.29 ml.kg^- 1.min^- 1) participated in the present study. Anthropometric and body composition variables (e.g., height, body mass, sitting height, age, BF%, body mass index, right and left finger 2D:4D ratios) were measured. The following fitness tests were also conducted: 30 - 15 Intermittent Fitness Test (VO_2max and HRmax), COD (5-0-5 agility test), and speed (10-30msprint test. HRmax and the training load were also measured and monitored using the Rate of Perceived Exertion during the 26 weeks.

RESULTS

There were associations between HRmax and VO_2max, between 2D and 4D lengths and Left and Right hand ratios. Also, in AW with Right and Left 4D. The CW and de ACWR with the Right 4D. There were other associations between physical test variables and workload variables.

CONCLUSIONS

Under-14 soccer players with low right and left-hand 2D:4D ratios did not perform better in the selected fitness tests to assess VO_2max, COD, or sprint ability. However, it cannot be ruled out that the absence of statistically significant results may be related to the small sample size and the maturational heterogeneity of the participants.