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The primary purpose of this study was to assess the sensitivity of cell-free DNA (cf-DNA) to different resistance training volume loads. The secondary purpose was to examine the relationship between change in cf-DNA and relative strength. Researchers hypothesized that (a) cf-DNA concentrations would increase with increasing volume load and (b) increases in relative strength would result in predicted decreases to %Δ of cf-DNA. Thirty subjects were recruited for this study, 15 men and 15 women. Blood was collected through venous draws into 4-ml vacutainers at 3 time points: immediately before (T1), after 3 sets (T2), and after 6 sets (T3) of the back squat exercise. A critical alpha of 0.05 was set for inferential statistics. A repeated-measures ANOVA showed that cf-DNA increased significantly from T1 (407.72 ± 320.83) to T2 (1,244.6 ± 875.83) (p < 0.01) and T1 (407.72 ± 320.83) to T3 (1,331.15 ± 1,141.66) (p < 0.01), whereas no difference was found from T2 to T3 (p = 1.00). The linear regression model used to examine the predictive capabilities relative strength had on cf-DNA %Δ from T1 to T3 was found to be significant (p = 0.04; R² = 0.15). The results of this study demonstrate the short response of cf-DNA in relation to variations in resistance training volume load. Results also demonstrated the positive relationship between relative strength and cf-DNA %Δ. The current study builds on the body of research that cf-DNA provides insight regarding the level of immune response after exercise training. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate acute effects of match-play on neuromuscular performance and subjective recovery and stress state and the relationship between training load (TL) and changes in neuromuscular performance in female soccer players. Twelve National Collegiate Athlete Association Division I players participated (20.7 ± 2.3 years; 64.4 ± 7.2 kg; 164.5 ± 6.0 cm) and completed countermovement jump (CMJ) at 0 kg (CMJ0) and 20 kg (CMJ20) and the Short Recovery Stress Scale (SRSS) at 3 hours pre-match (Pre), 12 hours post-match (Post12), and 38 hours post-match (Post38). Countermovement jump variables included body mass, jump height (JH), modified reactive strength index (RSI), peak force (PF), relative PF, eccentric impulse, concentric impulse (CI), peak power (PP), relative PP (RPP), eccentric average PP, and concentric average power (CAP). The SRSS consists of 4 Stress Scales (SSs) and 4 Recovery Scales (RSs). Training loads included total distance, total PlayerLoad, high-speed running, and session ratings of perceived exertion. Significant moderate to large decreases were observed from Pre to Post12 in JH, RSI, CI, PP, RPP, and CAP in CMJ0 and CMJ20 (p < 0.05, effect size [ES] = 0.63-1.35). Significant changes were observed from Pre to Post12 in all RSs (p < 0.05, ES = 0.65-0.79) and 3 SSs (p < 0.05, ES = 0.71-0.77). Significant correlations were observed between CMJ20 PP from Pre to Post12 and all TLs (p < 0.05, r520.58 to 20.68). CMJ0 and CMJ20 JH and PP may indicate acute neuromuscular changes after match-play. The magnitude of CMJ20 PP decrements from Pre to Post12 may be affected by soccer match-play volumes. [ABSTRACT FROM AUTHOR]