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Introduction Aims Methods Results Conclusion Limb dominancy has been suggested, by some, to influence arterial occlusion pressure (AOP). However, we hypothesized that the differences in AOP between the dominant and nondominant legs were more likely explained by differences in cuff position.To determine the impact of limb dominance, composition, and cuff position on AOP in the context of error associated with measuring AOP twice on the same leg.Fifty‐eight adults (30 males) volunteered to have AOP measured on their dominant legs with the cuff bladder covering their inner thighs and on their nondominant legs with the bladder covering their inner and outer thighs (in random order). Thigh circumference and muscle and fat thicknesses were also measured on each leg.We found evidence for differences in AOP between legs [median δ of −0.222, 95% credible interval: (−0.429, −0.016)] when the cuff position was matched. The mean difference was −2.8 mmHg, and the 95% limit of agreement in a Bland–Altman plot was −24.8 to 19.0 mmHg. When plotting this alongside an error range (i.e., 95% limits of agreement) of taking the same measurement twice from our previous study (Spitz et al., 2020), 52 out of 58 measurements were within the error range. This difference was not due to the cuff position. Additionally, there was no evidence that thigh circumference or composition (muscle/fat thickness) moderated any difference between limbs.The difference in AOP between limbs is small and is mostly indistinguishable from the difference observed from taking the measurement twice on the same limb. [ABSTRACT FROM AUTHOR]

It is currently unknown if individuals can be conditioned to a relative arterial occlusion pressure (AOP) and replicate that pressure at a later time point. The purpose of this study was to determine whether individuals can be taught to sense a certain relative pressure (i.e., target pressure) by comparing a conditioning method with a time-matched non-conditioning control. Fifty-eight subjects completed 2 visits in a randomized order: (a) conditioning condition and (b) time-matched control condition. The conditioning involved 11 series of inflations to 40% AOP for 12 seconds followed by cuff deflation for 22 seconds. The pressure estimations were taken at 5 and 30 minutes after each condition. Data are presented as mean differences (95% credible interval). The absolute error at 5 minutes was greater for the control compared with conditioning condition (7.1 [2.0-12.1] mm Hg). However, this difference in absolute error between conditioning and control was reduced at 30 minutes (2.9 [-1.3 to 7.1] mm Hg). The mean difference and 95% limits of agreement for the control were 8.2 (-42.4 to 58.5) mm Hg at 5 minutes and 0.02 (-43.5 to 43.5) at 30 minutes. The agreements for the conditioning were -6.2 (-32.4 to 20.0) mm Hg at 5 minutes and -11.2 (-36.6 to 14.3) mm Hg at 30 minutes. The results suggest that the individuals can be taught to sense the target pressure, but this effect only lasts a short amount of time. Future work is necessary to refine the conditioning method to extend the duration of this conditioning effect. [ABSTRACT FROM AUTHOR]

The article titled "Blood flow restriction training attenuates changes in local muscle endurance: At odds with previous work?" explores the effects of blood flow restriction on muscle endurance. The authors discuss previous studies and note the discrepancies in their findings. They emphasize the importance of exercise volume in improving muscle endurance and suggest that further research is needed to fully understand the mechanisms involved. The article includes a table summarizing the characteristics and results of 10 blood flow restriction training studies. The authors conclude that blood flow restriction may hinder improvements in local muscle endurance, contradicting previous research, and suggest that differences in training volume may be a contributing factor. However, more research is required to confirm these findings and fully comprehend the impact of blood flow restriction on muscle endurance. [Extracted from the article]

It was previously hypothesized that the cross-education of strength is asymmetrical, where a greater transfer of strength is observed from the dominant to the non-dominant limb. The purpose of this study was to examine if the magnitude of cross-education of strength differed between dominant and non-dominant limbs following unilateral high-load resistance training. One hundred and twenty-two participants were randomized to one of the three groups: 1) training on the dominant arm (D-Only), 2) training on the non-dominant arm (ND-Only) and 3) a time-matched non-exercise control (Control). The training groups completed 6 weeks (18 sessions) of unilateral elbow flexion exercise. Each training session started with one-repetition maximum (1RM) training (≤ five attempts), followed by four sets of high-load exercise (i.e. 8–12RM). Strength changes of the untrained arm were compared between groups. Changes in the strength of the untrained arm were greater in D-Only (1.5 kg) and ND-Only (1.3 kg) compared to Control (−0.2 kg), without differences between D-Only and ND-Only. Unilateral resistance training increased strength in the opposite untrained arm, and the magnitude of this effect was similar regardless of which arm was trained. However, there is still considerable uncertainty on this topic and additional research is warranted to confirm the current findings. [ABSTRACT FROM AUTHOR]

To determine (a) the impact of ischemic preconditioning pressures (applied as a % of arterial occlusion pressure [AOP]) on pressure pain threshold (PPT) and resistance exercise performance and (b) whether changes in performance could be explained by changes in PPT. Subjects (n539) completed 4 protocols in a randomized order: (a) ischemic preconditioning (IPC) at 110% AOP (IPC 110%), (b) IPC at 150% AOP (IPC 150%), (c) IPC at 10% AOP (Sham), and (d) time-matched control (CON). Each protocol included 4 cycles of 5 minutes of occlusion followed by 5 minutes of reperfusion. Pressure pain threshold was taken before and after. Discomfort ratings were given at the end of each cycle. Every visit finished with 2 sets of 75-second maximal isokinetic unilateral elbow flexion or extension. Overall, IPC 110% and IPC 150% resulted in similar increases in PPT relative to CON [110%: difference of 0.36 (0.18, 0.54) kg·m-2; 150%: difference of 0.377 (0.15, 0.59) kg·m-2] and Sham. Both resulted in greater discomfort than Sham and CON, with IPC 150% inducing greater discomfort than IPC 110% (BF10: 14.74). There were no differences between the conditions for total work (BF10: 0.23), peak torque (BF10: 0.035), or average power (BF10: 0.159). We did not find evidence that PPT mediated performance. We did not detect changes in performance with 2 different relative pressures greater than AOP. Our mean applied pressures were lower than those used previously. There might be a minimal level of pressure (e.g., >150% of AOP) that is required to induce ergogenic effects of ischemic preconditioning. [ABSTRACT FROM AUTHOR]

Objectives: (1) To examine the muscle thickness of various muscle groups of the body to estimate the absolute and relative skeletal muscle mass (SM) in competitive physique‐based athletes (Bodybuilding, 212 Bodybuilding, Bikini, and Physique divisions) and (2) to compare values across various divisions of competition and to resistance trained and non‐resistance trained individuals. Methods: Eight competitive physique‐based athletes (2 M and 6 F), two recreationally resistance trained (1 M and 1 F) and two non‐resistance trained (1 M and 1 F) participants had muscle thickness measured by ultrasound at nine sites on the anterior and posterior aspects of the body. SM was estimated from an ultrasound‐derived prediction equation and SM index was used to adjust for the influence of standing height (i.e., divided by height squared). Results: SM values ranged from 19.6 to 60.4 kg in the eight competitive physique‐based athletes and 16.1 to 32.6 kg in the four recreationally resistance trained and non‐resistance trained participants. SM index ranged from 7.2 to 17.9 kg/m2 in the eight competitive physique‐based athletes and 5.8 to 9.3 kg/m2 in the four recreationally resistance trained and non‐resistance trained participants. Conclusion: Overall, varying magnitudes of SM and SM index were present across competitors and their respective divisions of bodybuilding. The Men's Open Bodybuilder in the present study had greater values of total SM and SM index compared to previously published values in the literature. Our data provides insight into the extent of SM present in this population and further extends the discussion regarding SM accumulation in humans. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to examine the acute muscular and cardiovascular responses to applying blood flow restriction (BFR) before high‐load training. Methods: Forty trained individuals visited the lab on three occasions. On Visit 1, participants completed paperwork and performed strength assessments. During Visits 2 and 3, participants completed four exercise conditions (one in each arm during each visit) as follows: (1) traditional resistance training (TRAD), (2) low load training with BFR (LLBFR), (3) low repetition high load training with pre‐exercise BFR (PreBFR), and (4) low repetition traditional training (LRTRAD). Blood pressure, muscle thickness (MT), and isometric strength (ISO) were measured before and after exercise. Results: Data are displayed as means (SD). Immediately following exercise, MT in TRAD was greater compared with PreBFR (mean difference = 0.18[0.30] cm, p < 0.001) and LRTRAD (mean difference = 0.28[0.30] cm, p < 0.001). In addition, LLBFR demonstrated greater MT compared with PreBFR (mean difference = 0.24[0.30] cm, p < 0.001]. Immediately following exercise, ISO was lower in TRAD compared with PreBFR (mean difference = 33.8[46.9]N, p < 0.001) and the LRTRAD condition (mean difference = 32.8[50.4]N, p < 0.001). In addition, ISO was lower in LLBFR compared with PreBFR (mean difference = 43.9 [47.4]N, p < 0.001) and LRTRAD (mean difference = 42.9 [43.8]N, p < 0.001). Immediately following exercise, systolic blood pressure was greater in TRAD compared with PreBFR and LRTRAD. Conclusion: The application of BFR before engaging in high‐load training does not seem to augment the muscular responses to exercise when compared with traditional high loads alone; however, it may pose less demand on the cardiovascular system. [ABSTRACT FROM AUTHOR]

Aim: Within the resistance exercise literature, echo intensity (EI) is often quantified using different regions of interest (ROI). Purpose: To compare changes in the EI of images of the biceps muscle using different ROI immediately following exercise as well as 24 and 48 h following exercise. Methods: Twenty seven non‐resistance trained individuals visited the laboratory 4 times. One arm was assigned to the experimental condition, and the other was a non‐exercise control. During visit 1, paperwork and strength were measured. During visit, 2 participant's muscles were imaged before performing biceps curls. Additional muscle images were taken immediately after exercise, as well as 24 and 48 h post. EI was measured using three different ROI: 1) Trace around the entire muscle; 2) Small box placed in the middle of the muscle (2 × 2cm); and 3) Maximal rectangular box. Results are displayed as means (95%CI). Results: There was no condition (experimental vs. control) x time (pre, post, 24h and 48h) x box size (small, large, full trace) interaction (p = 0·592). However, there was a main effect for box size (p < 0·001). EI values were higher with the small box [28·2 (23·3, 33·1) AU] compared to the large box [26·8 (22·3, 31·2) AU, p = 0·016] and compared to the full trace [24·2 (20·3, 28·0) AU p < 0·001)]. In addition, EI values were higher with the large box compared to the full trace technique (p = 0·001). Conclusion: Similar changes in EI are detected when using different commonly used ROI for analysing EI. However, when larger ROI are examined, EI values appear to be lower. [ABSTRACT FROM AUTHOR]

To investigate the effects of high-intensity contractions and low-intensity contractions with and without blood flow restriction on changes in blood pressure and hemodynamic parameters. A total of 179 participants (18–35 years) were randomly assigned to one of three training groups that exercised 3 times per week for six weeks or a non-exercise control group. The groups are as follows: 1) Control [CON, n = 44]; 2) completed 4 sets of two-minute isometric contractions at 30% maximal voluntary contraction [LI, n = 47]; 3) completed 4 sets of two-minute isometric contractions at 30% maximal voluntary contraction with a 12 cm cuff inflated to 50% of arterial occlusion pressure [LI+BFR, n = 41]; or 4) completed 4 maximal isometric contractions lasting 5 seconds [MAX, n = 47]. Blood pressure, vascular resistance, and reactive hyperemia were measured at pre and post. Data are presented as means (SD). There was no evidence that SBP (BF10: 0.066), DBP (BF10: 0.057), vascular resistance (BF10: 0.085), or peak reactive hyperemia changed (BF10: 0.044) or A.U.C. (BF10: 0.074). Change scores for SBP were 1.1 (6.7), 0.7 (5.8), −0.4 (6.5), and −0.9 (6.3) mmHg for CON, LI, LI+BFR, and MAX, respectively. DBP change scores were 1.5 (6.6), 1.5 (7), −0.7 (5.9), and 0.3 (6.3) mmHg for CON, LI, LI+BFR, and MAX, respectively. Although recommended as a non-pharmacological method of blood pressure control, isometric exercise with or without BFR did not lower blood pressure. Future work could examine the inclusion of a daily strength test prior to the low intensity protocol. [ABSTRACT FROM AUTHOR]

Training one limb with a high-load has been shown to augment strength changes in the opposite limb training with a low-load (via cross-education of strength), indicating that within-subject models can be problematic when investigating strength changes. This study examined if the cross-education of strength from unilateral high-load training could augment the strength changes in the opposite arm undergoing the same unilateral high-load training. 160 participants were randomized to one of four groups: (1) training on the dominant arm followed by the non-dominant arm (D + ND), (2) training on the dominant arm only (D-Only), (3) training on the non-dominant arm only (ND-Only), and (4) a non-exercise control. All exercise groups performed 18 sessions of unilateral high-load elbow flexion exercise over 6 weeks. Participants were compared for changes in 1RM strength and muscle thickness. Changes in strength of the non-dominant arm were greater in D + ND (2.7 kg) and ND-Only (2.6 kg) compared to D-Only (1.5 kg) and control (-0.2 kg), while the changes were greater in D-Only compared to control. The same finding was observed in the dominant arm. Only the arms being directly trained observed increases in muscle thickness. Unilateral high-load resistance training increased strength in the opposite untrained arm, without changes in muscle thickness. This cross-education of strength did not augment the strength changes in the contralateral arm undergoing the same unilateral high-load training. However, it does not necessarily indicate that within-subject models are methodologically sound to investigate strength change if both limbs are trained with a high-load., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Abstract: Changes in skeletal muscle size may be affected by resting blood flow (e.g., nutrient delivery) and this change in size is a hypothesized mechanism for changes in strength., Purpose: To determine: 1) whether the relationship between isometric training and muscle growth depends on baseline blood flow or is mediated by a change in blood flow and 2) whether muscle growth mediates changes in maximal isometric strength., Methods: 179 participants were randomized into: low-intensity isometric handgrip exercise (LI), low-intensity isometric handgrip exercise with blood flow restriction (LI-BFR), maximal handgrip exercise (MAX), and a non-exercise control (CONTROL). Muscle thickness, strength, and resting limb blood flow were measured before and after the six-week intervention., Results: Baseline blood flow did not moderate training effects on muscle thickness changes (MTHchg) (p = 0.666), and moderated mediation tests were non-significant. Although the LI-BFR group showed a significant effect on MTHchg (p = 0.018), MTHchg was not significantly related to handgrip strength change (HGchg) (p = 0.281), suggesting no mediation of the training-to-strength effect by MTHchg. Both the LI-BFR (p = 0.004) and MAX (p < 0.001) groups exhibited positive direct effects on HGchg compared to CONTROL. Furthermore, there were no differences between training groups and CONTROL on blood flow change (BFchg), BFchg and MTHchg were not significantly related, and neither BFchg nor MTHchg predicted HGchg, providing no evidence for mediated pathways., Conclusions: Muscle growth may not have occurred to an extent that would require vascular adaptation. Training maximally induced the greatest strength adaptations but was seemingly not driven by muscle growth., Competing Interests: Conflict of Interest and Funding Source: This study received no funding. The authors declare that there is no conflict of interest related to the content of this article., (Copyright © 2024 by the American College of Sports Medicine.)

Progressive overload describes the gradual increase of stress placed on the body during exercise training, and is often quantified (i.e. in resistance training studies) through increases in total training volume (i.e. sets × repetitions × load) from the first to final week of the exercise training intervention. Within the literature, it has become increasingly common for authors to discuss skeletal muscle growth adaptations in the context of increases in total training volume (i.e. the magnitude progression in total training volume). The present manuscript discusses a physiological rationale for progressive overload and then explains why, in our opinion, quantifying the progression of total training volume within research investigations tells very little about muscle growth adaptations to resistance training. Our opinion is based on the following research findings: (1) a noncausal connection between increases in total training volume (i.e. progressively overloading the resistance exercise stimulus) and increases in skeletal muscle size; (2) similar changes in total training volume may not always produce similar increases in muscle size; and (3) the ability to exercise more and consequently amass larger increases in total training volume may not inherently produce more skeletal muscle growth. The methodology of quantifying changes in total training volume may therefore provide a means through which researchers can mathematically determine the total amount of external 'work' performed within a resistance training study. It may not, however, always explain muscle growth adaptations., (© 2024 Institute of Physics and Engineering in Medicine. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Abstract: Song, JS, Hammert, WB, Kataoka, R, Yamada, Y, Kang, A, and Loenneke, JP. Individuals can be taught to sense the degree of vascular occlusion: Implications for practical blood flow restriction. J Strength Cond Res 38(8): 1413-1418, 2024-It is currently unknown if individuals can be conditioned to a relative arterial occlusion pressure (AOP) and replicate that pressure at a later time point. The purpose of this study was to determine whether individuals can be taught to sense a certain relative pressure (i.e., target pressure) by comparing a conditioning method with a time-matched non-conditioning control. Fifty-eight subjects completed 2 visits in a randomized order: (a) conditioning condition and (b) time-matched control condition. The conditioning involved 11 series of inflations to 40% AOP for 12 seconds followed by cuff deflation for 22 seconds. The pressure estimations were taken at 5 and 30 minutes after each condition. Data are presented as mean differences (95% credible interval). The absolute error at 5 minutes was greater for the control compared with conditioning condition (7.1 [2.0-12.1] mm Hg). However, this difference in absolute error between conditioning and control was reduced at 30 minutes (2.9 [-1.3 to 7.1] mm Hg). The mean difference and 95% limits of agreement for the control were 8.2 (-42.4 to 58.5) mm Hg at 5 minutes and 0.02 (-43.5 to 43.5) at 30 minutes. The agreements for the conditioning were -6.2 (-32.4 to 20.0) mm Hg at 5 minutes and -11.2 (-36.6 to 14.3) mm Hg at 30 minutes. The results suggest that the individuals can be taught to sense the target pressure, but this effect only lasts a short amount of time. Future work is necessary to refine the conditioning method to extend the duration of this conditioning effect., (Copyright © 2024 National Strength and Conditioning Association.)

Objectives: This study compared muscle growth in response to very low load resistance training with direct pulsed current (DPC) stimulation and traditional high load training., Methods: Twenty-six resistance trained individuals had each leg assigned to one of two unilateral knee extension protocols: 1) 4 sets of 20 repetitions at ~10% one-repetition maximum (1RM) and inter-set rest periods of 30 s (DPC) and 2) 4 sets to muscular failure at ~70% 1RM (TRAD). Muscle thickness (MTH), 1RM strength, and local muscular endurance (LME) were measured before and after 8-weeks of training. An alpha level of 0.05 was used for all comparisons., Results: MTH increased similarly between TRAD and DPC at the 50% (0.24 cm, 95%CI: 0.11-0.36), and the 60% anterior sites (0.25 cm, 95%CI: 0.10-.040), as well as the lateral (0.25 cm, 95%CI: 0.10-.040) and medial sites (0.21 cm, 95%CI: 0.10-0.31), but was greater for TRAD at the 40% anterior site (0.3 cm, 95%CI: 0.16-0.43). Changes in 1RM were greater for TRAD (10.2 kg, 95%CI: 5.8-14.4). LME increased similarly between protocols (5 repetitions, 95%CI: 3-7)., Conclusions: The current data suggest that very low load knee extension resistance training with DPC could be a viable training strategy for promoting skeletal muscle growth and local muscular endurance., Competing Interests: The authors have no conflict of interest.

Objectives: To examine changes in muscle thickness (MT), soreness (SOR), and isometric torque (ISO) following exercise with pulsed direct current (Neubie) or traditional high-load (TRAD) exercise., Methods: Thirty-two participants had SOR, MT, and ISO measured before, immediately after, and 24 and 48h following TRAD and Neubie. Rating of perceived exertion (RPE) and discomfort were also measured. Results are displayed as means(SD)., Results: For MT, there was a condition x time interaction (p<0.001). For Neubie, MT increased pre [3.7(0.7)cm] to post [3.9(0.8) cm, p<0.001] and remained elevated at 24h. For TRAD, MT increased pre [3.7(0.6)cm] to post [4.0 (0.7)cm, p<0.001] and remained up to 48h. Greater values were observed for TRAD post-exercise. For ISO, both conditions decreased up to 48h. TRAD demonstrated a greater change post exercise (p<0.001). For SOR, both conditions increased up to 48h. Neubie demonstrated greater SOR at 48h (p=0.007). RPE was higher for all sets in TRAD [Mean across sets=16.0(1.9) vs. 13.5(2), p<0.001]. Discomfort was higher in all sets for Neubie [Mean across sets=5.8(1.5)vs. 4.5(2.0), p<0.05]., Conclusions: Both conditions showed increased SOR, and decreased ISO for up to 48h, with MT increased for up to 24h. MT remained elevated in TRAD at 48h. Neubie training might be effective for individuals who are looking to experience lower RPE responses during exercise., Competing Interests: The authors have no conflict of interest.