Effect of Blood Flow Restriction Training on Quadriceps Muscle Strength, Morphology, Physiology, and Knee Biomechanics Before and After Anterior Cruciate Ligament Reconstruction: Protocol for a Randomized Clinical Trial

Surface Electromyography and Gait Features in Patients after Anterior Cruciate Ligament Reconstruction

OBJECTIVE

An important reason for the poor recovery of anterior cruciate ligament (ACL) injuries is the poor recovery of muscle function. Therefore, we used surface electromyography (sEMG) and gait analysis to explore the muscle activation patterns and gait characteristics between lower limbs under different exercise states in patients, following anterior cruciate ligament reconstruction (ACLR).

METHODS

Forty-one adults with unilateral ACL injuries in Binzhou Medical University Hospital from October 2022 to June 2023 were allocated to three groups according to the time after ACL reconstruction: group A (≤3 months, 16), group B (3 months-1 year, 13), and group C (>1 year, 12). Patients were tested by sEMG and gait, while straight leg raising (SLR), walking at normal speed, fast walking, and walking up and down the stairs. Two related sample tests were performed for the normalized root mean square (RMS) values and gait parameters.

RESULTS

Muscle function changes varied in different training tasks. The RMS value of the involved side was more than the uninvolved side in biceps femoris and semitendinosus of group A (p < 0.010), and for the bilateral rectus femoris (RS), vastus medialis (VM), and vastus lateralis in group B, only the comparison of the RS was significant in group C during fast walking and going up and down the stairs. The ground impact (0.90 [0.63, 1.33] vs. 0.71 [0.43, 1.02], p = 0.035) of the uninvolved side was significantly decreased compared to those of the involved side in patients with ACLR when going down the stairs.

CONCLUSION

Different muscles need to be focused on at different stages of the postoperative period. sEMG and gait analysis can guide the development of a rehabilitation program.

Muscle Fiber Cross-Sectional Area Is Associated With Quadriceps Strength and Rate of Torque Development After ACL Injury

ABSTRACT

Graham, MC, Thompson, KL, Hawk, GS, Fry, CS, and Noehren, B. Muscle fiber cross-sectional area is associated with quadriceps strength and rate of torque development after ACL injury. J Strength Cond Res 38(6): e273-e279, 2024-The purpose of this study was to investigate the relationship between muscle fiber type-specific properties of the vastus lateralis and quadriceps muscle performance in individuals after an anterior cruciate ligament (ACL) tear. 26 subjects (22.0 ± 5.4 years) were included in this cross-sectional study, and all data were collected before ACL reconstruction. Quadriceps peak torque (QPT) and early (0-100 ms) and late (100-200 ms) rate of torque development (RTD) were obtained from maximal voluntary isometric quadriceps strength testing. Muscle fiber cross-sectional area (fCSA) and percent fiber type distribution (FT%) were evaluated through immunohistochemical analysis of a muscle biopsy. Between-limb differences in fiber characteristics were assessed using paired t-tests (with α-level 0.05). Relationships between fiber-specific properties and quadriceps muscle performance were determined using separate multiple linear regression analyses for ACL-injured and noninjured limbs. There were significant differences in fCSA between ACL-injured and noninjured limbs across all fiber types, but no differences in FT%. Type 1 fCSA, type 2a fCSA, and their interaction effect were the explanatory variables with the strongest relationship to all performance outcomes for the ACL-injured limb. The explanatory variables in the ACL-injured limb had a significant relationship to QPT and late RTD, but not early RTD. These findings suggest that QPT and late RTD are more heavily influenced by fCSA than FT% in ACL-injured limbs. This work serves as a foundation for the development of more specific rehabilitation strategies aimed at improving quadriceps muscle function before ACL reconstruction or for individuals electing nonsurgical management.

Effects of a Perioperative Blood Flow Restriction Therapy Program on Early Quadriceps Strength and Patient-Reported Outcomes After Anterior Cruciate Ligament Reconstruction

Background

Quadriceps muscle atrophy remains a limiting factor in returning to activity after anterior cruciate ligament reconstruction (ACLR). Blood flow restriction (BFR) therapy may accelerate quadriceps strengthening in the perioperative period.

Purpose

To evaluate postoperative isometric quadriceps strength in patients who underwent ACLR with a perioperative BFR program.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

Patients indicated for ACLR were randomized into 2 groups, BFR and control, at their initial clinic visit. All patients underwent 2 weeks of prehabilitation preoperatively, with the BFR group performing exercises with a pneumatic cuff set to 80% limb occlusion pressure placed over the proximal thigh. All patients also underwent a standardized postoperative 12-week physical therapy protocol, with the BFR group using pneumatic cuffs during exercise. Quadriceps strength was measured as peak and mean torque during seated leg extension and presented as quadriceps index (percentage vs healthy limb). Patient-reported outcomes (PROs), knee range of motion, and quadriceps circumference were also gathered at 6 weeks, 3 months, and 6 months postoperatively, and adverse effects were recorded.

Results

Included were 46 patients, 22 in the BFR group (mean age, 25.4 ± 10.6 years) and 24 in the control group (mean age, 27.5 ± 12.0 years). At 6 weeks postoperatively, the BFR group demonstrated significantly greater strength compared with the controls (quadriceps index: 57% ± 24% vs 40% ± 18%; P = .029), and the BFR group had significantly better Patient-Reported Outcomes Measurement Information System-Physical Function (42.69 ± 5.64 vs 39.20 ± 5.51; P = .001) and International Knee Documentation Committee (58.22 ± 7.64 vs 47.05 ± 13.50; P = .011) scores. At 6 weeks postoperatively, controls demonstrated a significant drop in the peak torque generation of the operative versus nonoperative leg. There were no significant differences in strength or PROs at 3 or 6 months postoperatively. Three patients elected to drop out of the BFR group secondary to cuff intolerance during exercise; otherwise, no other severe adverse events were reported.

Conclusion

Integrating BFR into perioperative physical therapy protocols led to improved strength and increased PROs at 6 weeks after ACLR. No differences in strength or PROs were found at 3 and 6 months between the 2 groups.

Registration

NCT04374968 (ClinicalTrials.gov identifier).

Effect of instrument-assisted soft tissue mobilization combined with blood flow restriction training on function, pain and strength of patients with patellofemoral joint pain

BACKGROUND

Patellofemoral pain syndrome is a prevalent sports injury that affects athletes both in their daily lives and during training. This condition causes pain in the area where the kneecap and thigh bone meet, and it can be quite debilitating. Whether an athlete is simply going about their day or pushing themselves to the limit during a workout, patellofemoral pain can be a significant hindrance.

PURPOSE

The purpose of this study is to investigate the impact of combining Instrument-Assisted Soft Tissue Mobilization (IASTM) treatment with blood flow restriction training on individuals with patellofemoral pain. Specifically, the study will assess improvements in pain levels, functional ability, strength, and joint mobility resulting from this treatment approach.

METHODS

Twenty-six patients diagnosed with patellofemoral pain were selected as observation subjects and randomly divided into two groups: the IASTM combined with blood flow restriction training treatment group (n = 13) and the IASTM treatment group alone (n = 13). The treatment period was 4 weeks. In this study, we conducted a comparison and analysis of the knee's visual analogue pain scale (VAS), Lysholm score, and a modified version of the Thomas test (MTT) at three different time points.In this subject paper, we compared and analyzed the VAS score of the knee, Lysholm score of the knee, and MTT at three different time points-before treatment, immediately after the first treatment, and after four weeks of treatment. Additionally, we recorded data using a maximum isometric muscle strength testing system for the lower extremity extensors four weeks before and after treatment.

RESULTS

In comparing the Lysholm scores within the groups, a significant difference was observed between the two groups following the initial treatment and after 4 weeks of treatment (p < 0.05). The scores increased, indicating a significant improvement in function. The VAS scores significantly differed after the first treatment and 4 weeks of treatment compared to before treatment (p < 0.05), indicating a significant improvement in pain. Additionally, after 4 weeks of treatment, the strength of the extensor muscle in the lower extremity significantly improved (p < 0.001). However, there was no significant difference in the strength test between the groups (p > 0.05). The MTT test revealed significant changes in the three joint angles before and after treatment (p > 0.05), suggesting an improvement in joint mobility. Overall, these results demonstrate the effectiveness of the treatment in improving pain and muscle strength in the lower extremity.

CONCLUSION

The combination of IASTM treatment and blood flow restriction has been shown to significantly reduce pain and improve periprosthetic soft tissue flexibility. Additionally, IASTM treatment alone was found to be more effective in improving knee pain and muscle flexibility, ultimately leading to increased knee strength in a pain-free state. In terms of the overall treatment outcome, it was found that the combined treatment was significantly more effective than the adjuvant soft tissue release treatment alone.

Electromyostimulation With Blood Flow Restriction for Patellofemoral Pain Syndrome in Active Duty Military Personnel: A Randomized Controlled Trial

INTRODUCTION

The high prevalence of patellofemoral pain in military service members results in strength loss, pain, and functional limitations during required physical performance tasks. Knee pain is often the limiting factor during high-intensity exercise for strengthening and functional improvement, thus limiting certain therapies. Blood flow restriction (BFR) improves muscle strength when combined with resistance or aerobic exercise and may serve as a possible alternative to high-intensity training during recovery. In our previous work, we showed that Neuromuscular electrical stimulation (NMES) improves pain, strength, and function in patellofemoral pain syndrome (PFPS), which led us to ask whether the addition of BFR to NMES would result in further improvements. This randomized controlled trial compared knee and hip muscle strength, pain, and physical performance of service members with PFPS who received BFR-NMES (80% limb occlusion pressure [LOP]) or BFR-NMES set at 20 mmHg (active control/sham) over 9 weeks.

METHODS

This randomized controlled trial randomly assigned 84 service members with PFPS to one of the two intervention groups. In-clinic BFR-NMES was performed two times per week, while at-home NMES with exercise and at-home exercise alone were performed on alternating days and omitted on in-clinic days. The outcome measures included strength testing of knee extensor/flexor and hip posterolateral stabilizers, 30-second chair stand, forward step-down, timed stair climb, and 6-minute walk.

RESULTS

Improvement was observed in knee extensor (treated limb, P < .001) and hip strength (treated hip, P = .007) but not flexor over 9 weeks of treatment; however, there was no difference between high BFR (80% LOP) and BFR-sham. Physical performance and pain measures showed similar improvements over time with no differences between groups. In analyzing the relationship between the number of BFR-NMES sessions and the primary outcomes, we found significant relationships with improvements in treated knee extensor strength (0.87 kg/session, P < .0001), treated hip strength (0.23 kg/session, P = .04), and pain (-0.11/session, P < .0001). A similar set of relationships was observed for the time of NMES usage for treated knee extensor strength (0.02/min, P < .0001) and pain (-0.002/min, P = .002).

CONCLUSION

NMES strength training offers moderate improvements in strength, pain, and performance; however, BFR did not provide an additive effect to NMES plus exercise. Improvements were positively related to the number of BFR-NMES treatments and NMES usage.

Survey of blood flow restriction therapy for rehabilitation in Sports Medicine patients

Background

Blood flow restriction (BFR) therapy has demonstrated benefits across a spectrum of musculoskeletal injuries, including improved strength, endurance, function, and reduction in pain perception. There is, however, no standardized application of BFR therapy among orthopaedic surgeons within the United States (US).

Hypothesis

The indication and protocol for BFR therapy vary significantly across providers in the US.

Methods

An online survey of 21 multiple-choice questions was sent to 3,281 surgeons listed on a large orthopaedic registry. A cross-sectional study was performed on all surgeons who successfully completed the questionnaire. Surgeons were queried on current or planned use of BFR, indications, contraindications, and peri-operative and non-operative management of sports-related injuries.

Results

Overall, 250 physicians completed the survey, with 149 (59.8%) reporting current BFR use and 75.2% initiating use in the last 1-5 years. Most protocols (78.8%) utilize the modality 2-3 times per week while 15.9% use it only once weekly. Anterior cruciate ligament reconstruction (ACLR) rehabilitation was the most reported indication for initiating BFR therapy (95.7%) along with medial patellofemoral ligament reconstruction (70.2%), multiligamentous knee reconstruction (68.8%), meniscus repair (62.4%), collateral ligament reconstruction (50.4%), Achilles tendon repairs (30.5%), and meniscectomy (27%). Only 36.5% reported using BFR after upper extremity procedures, such as distal biceps repair (19.7%), ulnar collateral ligament elbow reconstruction (17%), rotator cuff (16.8%), and shoulder labrum repair (15.3%). For non-operative injuries, 65.8% of surgeons utilized BFR. Of those not currently using BFR therapy, 33.3% intended to implement its use in the future.

Conclusion

BFR therapy has increased in popularity with most physicians implementing its use in the last 5 years. BFR was commonly utilized after ACLR.

Clinical relevance

BFR allows light-load resistance to simulate high-intensity resistance training. This study describes US orthopaedic surgeons' common practice patterns and patient populations that utilize BFR therapy.

Blood Flow Restriction Therapy for 2 Weeks Prior to Anterior Cruciate Ligament Reconstruction Did Not Impact Quadriceps Strength Compared to Standard Therapy

PURPOSE

To evaluate the efficacy of a 2-week home-based blood flow restriction (BFR) prehabiliation program on quadriceps strength and patient-reported outcomes prior to anterior cruciate ligament (ACL) reconstruction.

METHODS

Patients presenting with an ACL tear were randomized into two groups, BFR and control, at their initial clinic visit. Quadriceps strength was measured using a handheld dynamometer in order to calculate peak force, average force, and time to peak force during seated leg extension at the initial clinic visit and repeated on the day of surgery. All patients were provided education on standardized exercises to be performed 5 days per week for 2 weeks between the initial clinic visit and date of surgery. The BFR group was instructed to perform these exercises with a pneumatic cuff set to 80% of limb occlusion pressure placed over the proximal thigh. Patient-Reported Outcome Measurement System Physical Function (PROMIS-PF), knee range of motion, and quadriceps circumference were gathered at the initial clinic visit and day of surgery, and patients were monitored for adverse effects.

RESULTS

A total 45 patients met inclusion criteria and elected to participate. There were 23 patients randomized to the BFR group and 22 patients randomized into the control group. No significant differences were noted between the BFR and control groups in any demographic characteristics (48% vs 64% male [P = .271] and average age 26.5 ± 12.0 vs 27.0 ± 11.0 [P = .879] in BFR and control, respectively). During the initial clinic visit, there were no significant differences in quadriceps circumference, peak quadriceps force generation, time to peak force, average force, pain, and PROMIS scales (P > .05 for all). Following completion of a 2-week home prehabilitation protocol, all patients indeterminant of cohort demonstrated decreased strength loss in the operative leg compared to the nonoperative leg (P < .05 for both) However, there were no significant differences in any strength or outcome measures between the BFR and control groups (P > .05 for all). There were no complications experienced in either group, and both were compliant with the home-based prehabilitation program.

CONCLUSIONS

A 2-week standardized prehabilitation protocol preceding ACL reconstruction resulted in a significant improvement in personal quadriceps peak force measurements, both with and without the use of BFR. No difference in quadriceps circumference, strength, or patient reported outcomes were found between the BFR and the control group. The home-based BFR prehabiliation protocol was found to be feasible, accessible, and well tolerated by patients.

LEVEL OF EVIDENCE

Level II, randomized controlled trial with small effect size.

The effectiveness and safety of blood flow restriction training for the post-operation treatment of distal radius fracture

INTRODUCTION

Distal radius fracture (DRF) is a common injury in the upper extremities. Blood flow restriction (BFR) has been proven to be effective in improving function in low-load training, which is suitable for post-op rehabilitation. We explored the effectiveness and safety of BFR therapy in DRF patients who underwent surgery.

MATERIALS AND METHODS

Thirty-five patients were randomly assigned to either the BFR or the regular training (RT; no BFR therapy) groups. All patients completed the same 4-week postoperative rehabilitation program, including anti-inflammatory treatments, strengthening and range of motion (ROM) training. In the BFR group, the pressure was 120 mmHg in strengthening training course. Pain, circumferences of wrists and forearms, ROM, muscle strength, and D-dimer levels were evaluated at weeks 0, 2, and 4. Radius union scoring system (RUSS) was measured at weeks 4 and 12. Finally, wrist functionality (Cooney modification) was evaluated at week 12.

RESULTS

The BFR group had significantly decreased pain levels compared with the RT group (p < 0.01, effect size= 2.33, -2.44 at weeks 2 and 4). Swelling was effectively relieved in both groups. The wrist swelling was less in the BFR group (p < 0.01, effect size = -2.17 at week 4). The isometric strength of wrist extension (p < 0.01, effect size = 1.5, 3.02 at weeks 2 and 4), flexion (p < 0.01, effect size = 1.33, 2.53 at weeks 2 and 4), and functionality significantly increased in the BFR group (p < 0.01, effect size = 2.80 at week 12). No risk of VT in the BFR group was found. BFR did not threaten bone healing.

CONCLUSIONS

In patients with DRF who underwent corrective surgery, BFR therapy effectively relieved pain and swelling, increased muscle strength and wrist function, and had no additional risks for bone healing and VT.

An Automated Technique for the Measurement of Limb Occlusion Pressure During Blood Flow Restriction Therapy Is Equivalent to Previous Gold Standard

Purpose

Methods

Results

Conclusions

Level of Evidence

Blood Flow Restriction Training for Subacromial Pain: Two Case Reports

BACKGROUND

Blood flow restriction training (BFRT) appears to promote the strengthening of shoulder muscles, but primary clinical applications are limited to the lower extremity.

CASE PRESENTATION

Two female recreational athletes (Case A: 27 years old; Case B: 28 years old) with subacromial pain were treated with BFRT (50% occlusion) during 3 isotonic strengthening exercises of the upper extremity against 20% of the maximal isometric strength. At the beginning of each treatment week, we measured strength with a handheld dynamometer to ensure appropriate load progression.

OUTCOME AND FOLLOW-UP

Case A completed 16 visits and Case B completed 22 visits of BFRT with no adverse events. At discharge, we found meaningful improvement for patient-reported function, clinical measures of shoulder flexion and external-rotation range of motion and isometric strength, supraspinatus and infraspinatus cross-sectional area, and upper extremity performance.

DISCUSSION

BFRT may be a valuable adjunct to standard rehabilitation for the conservative management of subacromial pain. Despite the inherent limitations of our design, we believe these preliminary findings are compelling to warrant future investigations.

Blood flow Restriction training After patellar INStability (BRAINS Trial)

Background

Patellar instability is a common and understudied condition that disproportionally affects athletes and military personnel. The rate of post-traumatic osteoarthritis that develops following a patellar dislocation can be up to 50% of individuals 5–15 years after injury. Conservative treatment is the standard of care for patellar instability however, there are no evidence-informed rehabilitation guidelines in the scientific literature. The purpose of this study is to assess the effectiveness of blood-flow restriction training (BFRT) for patellar instability. Our hypotheses are that this strategy will improve patient-reported outcomes and accelerate restoration of symmetric strength and knee biomechanics necessary to safely return to activity.

Methods/design

This is a parallel-group, superiority, randomized, double-blinded, placebo-controlled clinical trial at the University of Kentucky, sports medicine clinic that aims to recruit 78 patients with acute patellar dislocations randomly allocated into two groups: (1) sham BFRT and (2) BFRT. Both groups will receive the current standard of care physical therapy 3 times per week for up to 9 weeks. Physical therapy sessions will consist of typical standard of care treatment followed by BFRT or sham BFRT. Primary outcomes include the Norwich Patellar Instability Scale, quadriceps strength, and imaging and biochemical biomarkers of cartilage degradation.

Discussion

The current standard of care for non-operative treatment of patellar instability is highly variable does not adequately address the mechanisms necessary to restore lower extremity function and protect the long-term health of articular cartilage following injury. This proposed novel intervention strategy uses an easily implementable therapy to evaluate if BFRT significantly improves patient-reported outcomes, function, and joint health over the first year of recovery.

Trial registration

Blood Flow Restriction Training, Aspiration, and Intraarticular Normal Saline (BRAINS) NCT04554212. Registered on 18 September 2020.

Use of rating of perceived exertion during anterior cruciate ligament reconstruction and knee osteoarthritis rehabilitation: a scoping review protocol

INTRODUCTION

Anterior cruciate ligament (ACL) tear and knee osteoarthritis (KOA) are the most prevalent musculoskeletal disorders of the knee. Rehabilitation with progressive resistance training is recommended for both disorders. Rating of perceived exertion (RPE) is widely used to prescribe, monitor, and control exercise load. However, the lack of detailed methodological description and variability in the use of RPE may hinder its validity. This scoping review summarises methodological aspects of the use of RPE in resistance exercises during ACL reconstruction and KOA rehabilitation. We also aim to identify possible methodological issues related to the use of RPE and provide recommendations for future studies.

METHODS AND ANALYSIS

This scoping review protocol was developed following the Joanna Briggs Institute and Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement extension for Scoping Reviews. The search will be conducted in Medline/PubMed, Embase, CINAHL, PEDro, Central and SPORTDiscus databases. The terms "anterior cruciate ligament rehabilitation", "knee osteoarthritis" and "resistance exercise" and their synonymous will be used isolated and combined (boolean operators AND/OR/NOT). Two reviewers will independently conduct title and abstract screening and evaluate full texts of potentially eligible articles. Data related to study design, sample, intervention characteristics and RPE outcomes will be extracted, summarised and qualitatively analysed.

ETHICS AND DISSEMINATION

The proposed scoping review does not require ethical approval since it will synthesise information from publicly available studies. Regarding dissemination activities, results will be submitted for publication in a scientific journal and presented at conferences in the field.

T1ρ imaging as a non-invasive assessment of collagen remodelling and organization in human skeletal muscle after ligamentous injury

Dysregulation and fibrosis of the extracellular matrix (ECM) in skeletal muscle is a consequence of injury. Current ECM assessment necessitates muscle biopsies to evaluate alterations to the muscle ECM, which is often not practical in humans. The goal of this study was to evaluate the potential of a magnetic resonance imaging sequence that quantifies T1ρ relaxation time to predict ECM collagen composition and organization. T1ρ imaging was performed and muscle biopsies obtained from the involved and non-involved vastus lateralis muscle on 27 subjects who had an anterior cruciate ligament (ACL) tear. T1ρ times were quantified via monoexponential decay curve fitted to a series of T1ρ-weighted images. Several ECM indices, including collagen content and organization, were obtained using immunohistochemistry and histochemistry in addition to hydroxyproline. Model selection with multiple linear regression was used to evaluate the relationships between T1ρ times and ECM composition. Additionally, the ACL-deficient and healthy limb were compared to determine sensitivity of T1ρ to detect early adaptations in the muscle ECM following injury. We show that T1ρ relaxation time was strongly associated with collagen unfolding (t = 4.093, P = 0.0007) in the ACL-deficient limb, and collagen 1 abundance in the healthy limb (t = 2.75, P = 0.014). In addition, we show that T1ρ relaxation time is significantly longer in the injured limb, coinciding with significant differences in several indices of collagen content and remodelling in the ACL-deficient limb. These results support the use of T1ρ to evaluate ECM composition in skeletal muscle in a non-invasive manner. KEY POINTS: Dysregulation and fibrotic transformation of the skeletal muscle extracellular matrix (ECM) is a common pathology associated with injury and ageing. Studies of the muscle ECM in humans have necessitated the use of biopsies, which are impractical in many settings. Non-invasive MRI T1ρ relaxation time was validated to predict ECM collagen composition and organization with aligned T1ρ imaging and biopsies of the vastus lateralis in the healthy limb and anterior cruciate ligament (ACL)-deficient limb of 27 subjects. T1ρ relaxation time was strongly associated with collagen abundance and unfolding in the ACL-deficient limb, and T1ρ relaxation time was strongly associated with total collagen abundance in the healthy limb. T1ρ relaxation time was significantly longer in the ACL-deficient limb, coinciding with significant increases in several indices of muscle collagen content and remodelling supporting the use of T1ρ to non-invasively evaluate ECM composition and pathology in skeletal muscle.

Biomechanics Analysis of the Lower Limbs in 20 Male Sprinters Using the International Society of Biomechanics Six-Degrees-of-Freedom Model and the Conventional Gait Model

BACKGROUND This biomechanics study of the lower limbs aimed to compare the use of the International Society of Biomechanics Six-Degrees-of-Freedom (ISB-6DOF) model and the conventional gait model (CGM), formerly known as the Helen Hayes model, in 20 male sprinters who habitually used the forefoot (FF) or rearfoot (RF) strike modes. MATERIAL AND METHODS We used a motion capture system to compare the difference in lower-extremity joint mechanics between sprinters' forefoot or rearfoot strike mode during unplanned sidestepping (UPSS). Twenty elite sprinters participated in a motion capture test under 2 models. Each of the 10 participants were classified as having a habitual forefoot strike mode or rearfoot strike mode during unplanned sidestepping. Joint mechanics and gait parameters were calculated according to the designed movement. RESULTS Comparison of the 2 models showed that the knee joint angles were inconsistent (P<0.05), highlighting the difficulty of the Helen Hayes model in anatomical recognition. The results of the 2 models show that during the unplanned sidestepping, the sprinter using the habitual rearfoot strike mode had a greater load through the knee joint (P<0.05). Sprinters who used the habitual forefoot strike mode experienced greater load through their ankle joints (P<0.05). CONCLUSIONS The findings from this biomechanics study showed that when compared with the ISB-6DoF model, the findings from the CGM were more reproducible for the evaluation of FF and RF strike during unplanned sidestepping.

Should We Trust Perceived Effort for Loading Control and Resistance Exercise Prescription After ACL Reconstruction?

CONTEXT

The rating of perceived effort (RPE) is a common method used in clinical practice for monitoring, loading control, and resistance training prescription during rehabilitation after rupture and anterior cruciate ligament reconstruction (ACLR). It is suggested that the RPE results from the integration of the afferent feedback and corollary discharge in the motor and somatosensory cortex, and from the activation of brain areas related to emotions, affect, memory, and pain (eg, posterior cingulate cortex, precuneus, and prefrontal cortex). Recent studies have shown that rupture and ACLR induce neural adaptations in the brain commonly associated with the RPE. Therefore, we hypothesize that RPE could be affected because of neural adaptations induced by rupture and ACLR.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 5.

RESULTS

RPE could be directly altered by changes in the activation of motor cortex, posterior cingulate cortex, and prefrontal cortex. These neural adaptations may be induced by indirect mechanisms, such as the afferent feedback deficit, pain, and fear of movement (kinesiophobia) that patients may feel after rupture and ACLR.

CONCLUSION

Using only RPE for monitoring, loading control, and resistance training prescription in patients who had undergone ACLR could lead to under- or overdosing resistance exercise, and therefore, impair the rehabilitation process.

STRENGTH-OF-RECOMMENDATION TAXONOMY

3C.

The perceptual responses of individuals with multiple sclerosis to blood flow restriction versus traditional resistance exercise

BACKGROUND

Low-load resistance exercise with blood flow restriction (_LLBFR-RE) has been shown capable of improving neuromuscular parameters in several clinical populations, however, its tolerability and effects on individuals with multiple sclerosis (MS) remains unknown.

OBJECTIVE

To investigate the perceptual responses of individuals with MS to _LLBFR-RE versus traditional high-load resistance exercise (HL-RE).

METHODS

Four men and eleven women diagnosed with relapsing-remitting MS randomly completed the following experimental trials: 1) _LLBFR-RE four sets of 30-15-15-15 repetitions, at 20% of one-repetition maximum (1-RM) of leg-press (LP) and knee-extension (KE), with 50% of BFR, and a 1-min rest interval between sets; 2) HL-RE- four sets of 8-10 repetitions, at 70% 1-RM of LP and KE, with the same rest intervals. Ratings of perceived exertion (RPE) were measured after each set, pain was measured before and after sets, and delayed-onset muscle soreness (DOMS) was measured at 5, 30, 60 min, and 24-h post-exercise.

RESULTS

HL-RE elicited significantly (p<0.05) greater RPE compared to _LLBFR-RE during all sets. Additionally, there were no significant (p>0.05) differences between _LLBFR-RE and HL-RE for pain immediately after all sets, although pain measured before sets were significantly (p<0.05) greater for _LLBFR-RE. Finally, both protocols resulted in similar DOMS, however, it was significantly (p<0.05) elevated 24-h post-exercise compared to 1-h after for HL-RE but not for _LLBFR-RE.

CONCLUSION

Altogether, these data demonstrate that _LLBFR-RE is well tolerated by individuals with MS, requires less muscular exertion than HL-RE, and does not cause exaggerated pain during exercise or elevated DOMS up to 24 h post-exercise.

Perioperative Blood Flow Restriction Rehabilitation in Patients Undergoing ACL Reconstruction: A Systematic Review

Background:

Low-load blood flow restriction (BFR) training has attracted attention as a potentially effective method of perioperative clinical rehabilitation for patients undergoing orthopaedic procedures.

Purpose:

To (1) compare the effectiveness of low-load BFR training in conjunction with a standard rehabilitation protocol, pre- and postoperatively, and non-BFR interventions in patients undergoing anterior cruciate ligament reconstruction (ACLR) and (2) evaluate protocols for implementing BFR perioperatively for patients undergoing ACLR.

Study Design:

Systematic review; Level of evidence, 2.

Methods:

A systematic review of the 3 medical literature databases was conducted to identify all level 1 and 2 clinical trials published since 1990 on BFR in patients undergoing ACLR. Patient demographics from included studies were pooled. Outcome data were documented, including muscle strength and size, and perceived pain and exertion. A descriptive analysis of outcomes from BFR and non-BFR interventions was performed.

Results:

A total of 6 studies (154 patients; 66.2% male; mean ± SD age, 24.2 ± 3.68 years) were included. Of these, 2 studies examined low-load BFR as a preoperative intervention, 1 of which observed a significant increase in muscle isometric endurance (P = .014), surface electromyography of the vastus medialis (P < .001), and muscle blood flow to the vastus lateralis at final follow-up (P < .001) as compared with patients undergoing sham BFR. Four studies investigated low-load BFR as a postoperative intervention, and they observed significant benefits in muscle hypertrophy, as measured by cross-sectional area; strength, as measured by extensor torque; and subjective outcomes, as measured by subjective knee pain during session, over traditional low-load resistance training (all P < .05). BFR occlusion periods ranged from 3 to 5 minutes, with rest periods ranging from 45 seconds to 3 minutes.

Conclusion:

This systematic review found evidence on the topic of BFR rehabilitation after ACLR to be sparse and heterogeneous likely because of the relatively recent onset of its popularity. While a few authors have demonstrated the potential strength and hypertrophy benefits of perioperative BFR, future investigations with standardized outcomes, long-term follow-up, and more robust sample sizes are required to draw more definitive conclusions.