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Blood flow restriction (BFR) training has been shown to induce exercise-induced muscle damage (EIMD) in some cases, although findings are inconsistent and the influence of the applied arterial occlusion pressure (AOP) remains unclear. This single-blind, randomized controlled trial investigated the effects of different percentages of AOP on EIMD and acute physiological responses in 40 participants allocated to four groups: no pressure (NP), low pressure (LP; 50% AOP), medium pressure (MP; 75% AOP), and high pressure (HP; 100% AOP). Participants performed unilateral knee extensions at 30% of their one-repetition maximum up to four sets of 20 repetitions or until failure. EIMD was primarily assessed by the changes in isokinetic peak torque 24 h, 48 h and 72 h post-exercise (Δ to baseline). Secondary markers included perceived pain, blood biomarkers (creatine kinase, myoglobin) and muscle swelling. Additionally, acute physiological responses were assessed, including continuous measurement of muscle oxygen saturation (SmO 2 ) during exercise, perceived exertion (RPE) immediately after the exercise bout, and blood lactate concentration measured at 1, 3, 7, and 10 min post-exercise. NP showed greater strength loss at 24 h post-exercise compared to MP (MD = − 9.95, p  = .042, 95% CI [− 19.7, − 0.19]) and HP (MD = − 10.51, p  = .034, 95% CI [− 20.52, − 0.49]). Pain ratings were higher in NP compared to MP ( p  = .001) and HP ( p  = .003) at 24 h post, and remained elevated at 48 h compared to MP ( p  = .003) and HP ( p  = .047). NP and LP completed more repetitions than MP and HP. HP exhibited a greater reduction in SmO 2 compared to NP. Perceived exertion was higher in MP and HP. LP showed higher average lactate concentrations than NP ( p  = .020). CK and MB responses showed no time-specific group differences. These findings suggest that BFR training, even at higher pressures, does not increase EIMD compared to free-flow exercise, and that MP and HP may even attenuate strength loss and pain following exercise.

Background The effects of Blood Flow Restriction (BFR) training are well-established, but its impact on the inflammatory response remains unclear. This systematic review evaluates whether BFR training induces acute inflammation by analyzing changes in inflammatory parameters. Methods This review was conducted according to PRISMA guidelines. The literature search was performed across PubMed, Web of Science, BISp-Surf and Google Scholar up to July 2025. Studies were included if they reported acute changes in inflammatory markers within 72 h after BFR training, as well as macrophage presence up to 14 days. Only trials involving healthy adults with inflammatory parameters assessed via peripheral blood or muscle biopsy were considered. Risk of bias was assessed using RoB 2 and ROBINS-I. Standardized mean differences (SMDs) were calculated to quantify within-study changes. In addition, relative percentage changes were calculated to enable a comparison of the magnitude of inflammatory responses across studies. An effect direction plot was created to summarize the direction of inflammatory marker changes (SWiM 2020). Results Nine studies involving 189 healthy adults were included in the systematic review. Transient increases in total leukocytes (18–33%) and lymphocytes (37–43%) were consistently observed in peripheral blood following exercise. Significant increases in total tissue macrophages (200%) were also reported. Findings on neutrophils (up to + 40%), cytokines (up to + 340%), and lymphocyte subpopulations (TCD4⁺: +25%, TCD8⁺: +39%) varied across studies. Conclusion The findings suggest that BFR training induces acute inflammation, characterized by transient leukocytosis, lymphocytosis, and increased macrophage activity. However, the variability in neutrophil and cytokine responses, as well as in lymphocyte subsets, may be attributed to variations in training parameters and methodological approaches. Overall, these responses appear comparable to those observed following high-load resistance training (HL-RT). Further research is needed to clarify the underlying mechanisms and their potential contribution to muscle adaptation. Key Points BFR training can induce acute changes in inflammatory markers, including transient increases in circulating total leukocyte and lymphocyte counts and a sustained presence of macrophages in muscle tissue. Neutrophil and cytokine responses, as well as lymphocyte subsets, showed variability across studies. The magnitude of immune cell responses following BFR training appear similar to that observed after HL-RT, where immune cell recruitment has been linked to regenerative processes. These responses, particularly the sustained presence of M2 macrophages, raise the possibility that inflammation following BFR training may also contribute to muscle regeneration. Further research is needed to clarify the underlying mechanisms and potential role of BFR-induced inflammation in muscle adaptation. Standardized training and measurement protocols are also required to improve comparability.

Tensiomyography (TMG) is a non-invasive method for measuring contractile properties of skeletal muscle that is increasingly being used in research and practice. However, the lack of standardization in measurement protocols mitigates the systematic use in sports medical settings. Therefore, this study aimed to investigate the effects of lower leg fixation and sensor location on TMG-derived parameters. Twenty-two male participants underwent TMG measurements on the m. biceps femoris (BF) in randomized order with and without lower leg fixation (fixed vs. non-fixed). Measurements were conducted at 50% of the muscle’s length (BF-mid) and 10 cm distal to this (BF-distal). The sensor location affected the contractile properties significantly, both with and without fixation. Delay time (T d ) was greater at BF-mid compared to BF-distal (fixed: 23.2 ± 3.2 ms vs. 21.2 ± 2.7 ms, p = 0.002; non-fixed: 24.03 ± 4.2 ms vs. 21.8 ± 2.7 ms, p = 0.008), as were maximum displacement (D m ) (fixed: 5.3 ± 2.7 mm vs. 3.5 ± 1.7 mm, p = 0.005; non-fixed: 5.4 ± 2.5 mm vs. 4.0 ± 2.0 mm, p = 0.03), and contraction velocity (V c ) (fixed: 76.7 ± 25.1 mm/s vs. 57.2 ± 24.3 mm/s, p = 0.02). No significant differences were revealed for lower leg fixation (all p > 0.05). In summary, sensor location affects the TMG-derived parameters on the BF. Our findings help researchers to create tailored measurement procedures in compliance with the individual goals of the TMG measurements and allow adequate interpretation of TMG parameters.

PurposeMuscular strength loss and atrophy are postoperative complications. This systematic review with meta-analysis investigated the course of on knee extensor mass and strength from pre-surgery over total knee arthroplasty to rehabilitation and recovery.MethodsA systematic literature search was conducted in PubMed (Medline), Cochrane Library (CINAHL, Embase) and Web of Science (until 29th of June 2022). Main inclusion criteria were  ≥ 1 preoperative and  ≥ 1 measurement  ≥ 3-months post-operation and ≥ 1 objective assessment of quadriceps strength, muscle mass or neuromuscular activity, measured at both legs. Studies were excluded if they met the following criteria: further impairment of treated extremity or of the contralateral extremity; further muscle affecting disease, or muscle- or rehabilitation-specific intervention. The Robins-I tool for non-randomized studies, and the Cochrane Rob 2 tool for randomized controlled studies were used for risk of bias rating. Pre-surgery, 3 months, 6 months and 1 year after surgery data were pooled using random effects meta-analyses (standardized mean differences, SMD, Hedge’s g) in contrast to the pre-injury values.Results1417 studies were screened, 21 studies on 647 participants were included. Thereof, 13 were non-randomized controlled trails (moderate overall risk of bias in most studies) and 7 were randomized controlled trials (high risk of bias in at least one domain in most studies). Three (k = 12 studies; SMD = − 0.21 [95% confidence interval = − 0.36 to − 0.05], I2 = 4.75%) and six (k = 9; SMD = − 0.10 [− 0.28 to − 0.08]; I2 = 0%) months after total knee arthroplasty, a deterioration in the strength of the operated leg compared with the strength of the non-operated leg was observed. One year after surgery, the operated leg was stronger in all studies compared to the preoperative values. However, this increase in strength was not significant compared to the non-operated leg (k = 6, SMD = 0.18 [− 0.18 to 0.54], I2 = 77.56%).ConclusionWe found moderate certainty evidence that deficits in muscle strength of the knee extensors persist and progress until 3 months post-total knee arthroplasty in patients with end-stage knee osteoarthritis. Very low certainty evidence exists that preoperatively existing imbalance of muscle strength and mass in favor of the leg not undergoing surgery is not recovered within 1 year after surgery.

PurposeHamstring injuries in soccer reportedly increase towards the end of the matches’ halves as well as with increased match frequency in combination with short rest periods, possibly due to acute or residual fatigue. Therefore, this study aimed to investigate the effects of acute and residual muscle fatigue on exercise-induced hamstring muscle damage.MethodsA three-armed randomized-controlled trial, including 24 resistance-trained males, was performed allocating subjects to either a training group with acute muscle fatigue + eccentric exercise (AF/ECC); residual muscle fatigue + eccentric exercise (RF/ECC) or a control group with only eccentric exercise (ECC). Muscle stiffness, thickness, contractility, peak torque, range of motion, pain perception, and creatine kinase were assessed as muscle damage markers pre, post, 1 h post, and on the consecutive three days.ResultsSignificant group × time interactions were revealed for muscle thickness (p = 0.02) and muscle contractility parameters radial displacement (Dm) and contraction velocity (Vc) (both p = 0.01), with larger changes in the ECC group (partial η2 = 0.4). Peak torque dropped by an average of 22% in all groups; stiffness only changed in the RF/ECC group (p = 0.04). Muscle work during the damage protocol was lower for AF/ECC than for ECC and RF/ECC (p = 0.005).ConclusionHamstring muscle damage was comparable between the three groups. However, the AF/ECC group resulted in the same amount of muscle damage while accumulating significantly less muscle work during the protocol of the damage exercise.Trial registrationThis study was preregistered in the international trial registration platform (WHO; registration number: DRKS00025243).

Tensiomyography (TMG) is a non-invasive method for measuring contractile properties of skeletal muscle that is increasingly being used in research and practice. However, the lack of standardization in measurement protocols mitigates the systematic use in sports medical settings. Therefore, this study aimed to investigate the effects of lower leg fixation and sensor location on TMG-derived parameters. Twenty-two male participants underwent TMG measurements on the m. biceps femoris (BF) in randomized order with and without lower leg fixation (fixed vs. non-fixed). Measurements were conducted at 50% of the muscle's length (BF-mid) and 10 cm distal to this (BF-distal). The sensor location affected the contractile properties significantly, both with and without fixation. Delay time (Td) was greater at BF-mid compared to BF-distal (fixed: 23.2 ± 3.2 ms vs. 21.2 ± 2.7 ms, p = 0.002; non-fixed: 24.03 ± 4.2 ms vs. 21.8 ± 2.7 ms, p = 0.008), as were maximum displacement (Dm) (fixed: 5.3 ± 2.7 mm vs. 3.5 ± 1.7 mm, p = 0.005; non-fixed: 5.4 ± 2.5 mm vs. 4.0 ± 2.0 mm, p = 0.03), and contraction velocity (Vc) (fixed: 76.7 ± 25.1 mm/s vs. 57.2 ± 24.3 mm/s, p = 0.02). No significant differences were revealed for lower leg fixation (all p > 0.05). In summary, sensor location affects the TMG-derived parameters on the BF. Our findings help researchers to create tailored measurement procedures in compliance with the individual goals of the TMG measurements and allow adequate interpretation of TMG parameters.

Animal studies have shown an exponential increase in the risk of Borrelia burgdorferi infection after 48–72 h of deer tick attachment. Persons with tick bites were prospectively studied to determine if those with prolonged tick attachment constitute a high-risk group for infection. Ticks were identified, measured for engorgement, and assayed by polymerase chain reaction (PCR) for B. burgdorferi DNA. Duration of attachment was determined from the scutal index of engorgement. Of 316 submissions, 229 were deer ticks; 14% were positive by PCR. Paired sera and an intact tick for determination of duration of attachment were available for 105 subjects (109 bites). There were 4 human cases (3.7% of bites) of B. burgdorferi infection. The incidence was significantly higher for duration of attachment ⩾72 h than for <72 h: 3 (20%) of 15 vs. 1 (1.1%) of 94 (P = .008; odds ratio, 23.3; 95% confidence interval, 2.2–242). PCR was an unreliable predictor of infection. Tick identification and measurement of engorgement can be used to identify a small, high-risk subset of persons who may benefit from antibiotic prophylaxis.

Abstract Integrase inhibitors (INSTIs) are recommended by expert panels as initial therapy for people with HIV. Because there can be disparities in prescribing and uptake of novel and/or recommended therapies, this analysis assessed potential INSTI prescribing disparities using a combined data set from the Johns Hopkins HIV Clinical Cohort and the DC Cohort. We performed multivariable logistic regression to identify factors associated with ever being prescribed an INSTI. Disparities were noted, including clinic location, age, and being transgender. Identifying disparities may allow clinicians to focus their attention on these individuals and ensure that therapy decisions are grounded in valid clinical reasons. We assessed INSTI prescribing disparities using Johns Hopkins HIV Clinical Cohort/DC Cohort data. Disparities were noted, including clinic location, age, and being transgender. Clinicians should focus their attention on these individuals and make therapy decisions grounded in valid clinical reasons.