Strength training with and without arteriovenous blood flow restriction improves performance, regardless of changes in muscle hypertrophy, in Wistar rats

Q: What are the key findings of this study?

Strength training with blood flow restriction increased manual grip strength by 37% and maximum loaded weight by 34% while increasing plantar muscle hypertrophy in Wistar rats.

Q: What is the clinical evidence from this study?

Population: Healthy male Wistar Hannover rats undergoing strength training and surgical arteriovenous blood flow restriction (n=52). Intervention: Strength training with arteriovenous blood flow restriction (T/BFR) vs. Sedentary sham (S/S), sedentary with BFR (S/BFR), and strength trained sham (T/S). Primary outcome: Manual grip strength (MGS), maximum loaded weight (MLW), and skeletal muscle hypertrophy index (p=<0.001).

Q: What does this research mean for the field?

Strength training with blood flow restriction increases manual grip strength and maximum loaded weight while inducing plantar muscle hypertrophy in Wistar rats without causing cardiovascular damage. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Q: What question did this study set out to answer?

To assess whether strength training combined with arterial blood flow restriction improves muscular adaptations, physical performance, and safety markers in Wistar rats.

Nádia Fagundes Garcia; Camila de Moraes; Macário Arosti Rebelo; Savanah Maria Gertrudis Rosa Peters; Fábio Marzliak Pozzi de Castro; Enrico Fuini Puggina

doi:10.1590/0001-3765202220201147

January 1, 2022Anais da Academia Brasileira de CiênciasOpen Access

Strength training with and without arteriovenous blood flow restriction improves performance, regardless of changes in muscle hypertrophy, in Wistar rats

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Key result

Strength training with blood flow restriction boosts grip strength by ~37% in preclinical models.

P<0.001
n=52

Why the study?

The effects of arterial blood flow restriction during strength training on muscle adaptations and safety are not well established.

Does strength training combined with surgical arteriovenous blood flow restriction improve muscular hypertrophy and strength performance without causing adverse cardiovascular or inflammatory effects in Wistar rats?

Key Points

To assess whether strength training combined with arterial blood flow restriction improves muscular adaptations, physical performance, and safety markers in Wistar rats.
Eight-week-old Wistar rats were assigned to four groups: sedentary sham (S/S, n=16), sedentary with blood flow restriction (S/BFR, n=12), trained sham (T/S, n=12), and trained with blood flow restriction (T/BFR, n=12).
The exercise protocol consisted of 4 weeks of ladder climbing (6 sets of 10 repetitions at 50% of 1 maximal voluntary contraction) with a blood flow restriction rate of 36% to 38%.
Measures included maximum loaded weight, manual grip strength, muscle hypertrophy index of the plantar, gastrocnemius, and soleus, systolic blood pressure, superoxide dismutase activity, nitrite/nitrate concentrations, and tumor necrosis factor alpha.
Maximum loaded weight increased by 31% in T/S and 34% in T/BFR (p < 0,001 vs S/S and S/BFR), while manual grip strength rose by 28% in T/S and 37% in T/BFR (p < 0,001 vs all groups).
Plantar muscle hypertrophy index increased in T/BFR compared to S/S (p = 0,027) and T/S (p = 0,028), while training alone without restriction did not stimulate hypertrophy.
No significant group differences emerged for systolic blood pressure (p = 0,235), superoxide dismutase (p = 0,085), or nitrite/nitrate concentrations (p = 0,164), although TNF-α increased in restriction groups (p < 0,001).

Structured PICO

Does strength training combined with surgical arteriovenous blood flow restriction improve muscular hypertrophy and strength performance without causing adverse cardiovascular or inflammatory effects in Wistar rats?

P

Population

52 male Wistar Hannover rats (8 weeks old, 250-270g) divided into four surgical/training groups and followed for 4 weeks of strength training.

I

Intervention

Strength training with surgical arteriovenous blood flow restriction (T/BFR; 36%-38% BFR rate via right superficial femoral artery and vein partial occlusion with 4-0 nylon thread), consisting of 6 sets of 10 vertical ladder climbs carrying 50% of 1 maximal voluntary contraction (MVC) plus body weight, 1-minute rest between sets, once daily, 3 days/week for 4 weeks.

C

Comparator

Sedentary sham surgery (S/S, n=16), sedentary with surgical BFR (S/BFR, n=12), and trained sham surgery undergoing the identical 4-week strength training protocol without vascular occlusion (T/S, n=12).

O

Outcome

Physical performance (maximum loaded weight [MLW] and manual grip strength [MGS]) and muscular hypertrophy index (ratio of soleus, plantar, and gastrocnemius muscle weight to tibia length in mg/mm) at 4 weeks.surrogate

Main Result

Absolute Event Rate: 37% vs 28%

p-value: p=<0.001

In a rat model, 4 weeks of low-load strength training with arteriovenous blood flow restriction enhanced grip strength and plantar muscle hypertrophy more than training alone without altering blood pressure or nitric oxide levels, although it increased systemic TNF-α.

Limitations

Manual grip strength test is dependent on examiner manipulation (e.g., traction force magnitude and angle applied to the tail)
Only plantar, soleus, and gastrocnemius muscles were evaluated for hypertrophy, omitting muscles like flexor hallucis longus or flexor digitorum longus
Food intake and total body fat mass were not directly assessed
Manual grip strength (MGS) test is dependent on examiner manipulation, including variations in traction force magnitude and angle applied to the animal's tail.
Hypertrophy was only evaluated in the plantar, soleus, and gastrocnemius muscles, excluding muscles heavily involved in ladder climbing grabbing ability such as the flexor digitorum longus (FDL) or flexor hallucis longus (FHL).
Food intake and total body fat composition were not measured (only epididymal fat was weighed).

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Implication

Rat model data suggest blood flow restriction may boost training gains; leaves open safe human clinical translation.

Abstract

Strength training (ST) with blood flow restriction (BFR) is known to promote increases in hypertrophy and strength sometimes similar to traditional ST despite the effects of the arterial BFR on muscle adaptations and safety are not well established. The aim of this study was to assess whether ST with arterial BFR is able to improve muscular adaptations, performance and its safety in Wistar rats. Animals aging 8 weeks were divided in four groups: sedentary sham (S/S), sedentary with arterial BFR (S/BFR), trained sham (T/S), and trained with arterial BFR (T/BFR). Training protocol consisted of four weeks of ST composed by six sets of 10 ladder climbing with 50% of 1 maximal voluntary contraction. Body weight, epididymal fat, maximum loaded weight, manual grip strength, muscular hypertrophy index, systolic blood pressure, enzyme activity of superoxide dismutase, nitrite/nitrate concentration and tumor necrosis factor alpha were analyzed. The BFR rate was between 36% and 38%. T/BRF was effective to promote strength and hypertrophy. T/S is an alternative to improve strength, but it did not promote hypertrophy. Furthermore, we found no significant cardiac and metabolic changes. Thus, T/BFR is able to improve muscle adaptations and performance in rats, without causing cardiovascular and metabolic damage.

Discussion

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Cite This Study

Garcia et al. (2022) studied Healthy male Wistar Hannover rats undergoing strength training and surgical arteriovenous blood flow restriction (n=52). Strength training with arteriovenous blood flow restriction (T/BFR) vs. Sedentary sham (S/S), sedentary with BFR (S/BFR), and strength trained sham (T/S) was evaluated on Manual grip strength (MGS), maximum loaded weight (MLW), and skeletal muscle hypertrophy index (p=<0.001). Strength training with blood flow restriction increased manual grip strength by 37% and maximum loaded weight by 34% while increasing plantar muscle hypertrophy in Wistar rats.

synapsesocial.com/papers/6a7f074b0652253f66c310b8 https://doi.org/10.1590/0001-3765202220201147

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Strength training with and without arteriovenous blood flow restriction improves performance, regardless of changes in muscle hypertrophy, in Wistar rats

Key Points

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Strength training with and without arteriovenous blood flow restriction improves performance, regardless of changes in muscle hypertrophy, in Wistar rats

Key Points

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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