Purpose: To assess the foot posture and hip joint mobility of elite handball and soccer players and to investigate possible correlations between these measurements. Methods: We compared the ...differences in means of Foot Posture Index (FPI), passive hip internal (IR), and external (ER) rotation range of motion (ROM) between three groups of male subjects (17 handball players, 17 soccer players, and 16 non-athletes). The Kruskal-Walli’s test and post-hoc pairwise comparison with the Mann-Whitney U test were used to determine the differences between the group means, and associations between variables were analyzed with Spearman’s correlation coefficient. Results: No significant differences in the mean FPI were found between the soccer players (1.3 ± 2.9), handball players (0.7 ± 2.1), and the control group (1.7 ± 2.5) (p > 0.05). Similarly, no significant difference was found between the groups in the hip ER ROM. In contrast, a significantly lower (p < 0.05) hip IR ROM was observed in the soccer players (30.6° ± 5.3°) compared to the handball players (41.0° ± 8.1°) and the control group (41.1° ± 6.4°). A weak positive correlation was only observed between the FPI and hip IR ROM in the soccer players (ρ: 0.36, p = 0.035). Conclusions: Handball and soccer players show a tendency toward less pronated feet compared to non-athletes, but the differences are not significant and the mean FPI values are still within the range of normal foot posture. The range of hip IR seems to be reduced in soccer players and weakly, but significantly and positively associated with the FPI value, which needs to be further investigated in future studies.
Surgical ACL reconstruction performed with a tourniquet induces compression and ischemic stress of the quadriceps femoris (QF) muscle which can accelerate postoperative weakness. Given that low-load ...blood flow restricted (BFR) exercise is potent in enhancing muscle oxygenation and vascular function, we hypothesized that short-term preconditioning with low-load BFR exercise can attenuate QF muscle endurance deterioration in the postoperative period. Twenty subjects undergoing arthroscopic ACL reconstruction performed 5 exercise sessions in the last 8 days prior to surgery. They were assigned into either BFR group, performing low-load BFR knee-extension exercise, or SHAM-BFR group, replicating equal training volume with sham occlusion. Blood flow (near-infrared spectroscopy) and surface EMG of QF muscle during sustained isometric contraction at 30% of maximal voluntary isometric contraction (MVIC) torque performed to volitional failure were measured prior to the intervention and again 4 and 12 weeks after surgery. There was an overall decrease (
= 0.033) in MVIC torque over time, however, no significant time-group interaction was found. The time of sustained QF contraction shortened (
= 0.002) in SHAM-BFR group by 97 ± 85 s at week 4 and returned to preoperative values at week 12. No change in the time of sustained contraction was detected in BFR group at any time point after surgery. RMS EMG amplitude increased (
= 0.009) by 54 ± 58% at week 4 after surgery in BFR group only. BFm increased (
= 0.004) by 52 ± 47% in BFR group, and decreased (
= 0.023) by 32 ± 19% in SHAM-BFR group at week 4 after surgery. Multivariate regression models of postoperative changes in time of sustained QF contraction revealed its high correlation (
= 0.838;
< 0.001) with changes in BFm and RMS EMG in the SHAM-BFR group, whereas no such association was found in the BFR group. In conclusion, enhanced endurance of QF muscle was triggered by combination of augmented muscle fiber recruitment and enhanced muscle perfusion. The latter alludes to a preserving effect of preconditioning with BFR exercise on density and function of QF muscle microcirculation within the first 4 weeks after ACL reconstruction.
Purpose: Restricting chest movement when carrying a loaded backpack reduces efficiency and increases the work of the respiratory muscles. The aim of the present study was to investigate the effects ...of six weeks of inspiratory muscle training (IMT) on respiratory muscle strength and endurance and on physical performance when carrying a load. Methods: Twenty male (age: 32.2 ± 3.4 years) members of the Special Operations Unit of the Slovenian Army volunteered to participate. The experimental group (n=10) trained their respiratory muscles for six weeks against an incremental inspiratory resistance with a breathing apparatus. The placebo group (n=10) performed the same IMT protocol but with a sham inspiratory resistance. Assessment of the subjects before and after IMT included measurements of the maximal inspiratory and expiratory pressures, heart rate measurements, and ratings of perceived physical and respiratory exertion before and after a 60-min walk test with a 25-kg backpack. Results: After six weeks of IMT, the maximum inspiratory pressure measured before and after the 60-minute walk test increased significantly (p < 0.001) in the experimental group by 47 ± 13% and 58 ± 20%, respectively. Inspiratory fatigue was also significantly lower in the experimental group. No changes were observed in the heart rate and the rating of perceived exertion during the walking test. In the placebo group, no significant changes were observed in the measured parameters after IMT.Conclusion: Six weeks of IMT with progressive breathing resistance improves strength and reduces fatigue of the respiratory muscles. Individuals who perform tasks that require them to carry a heavy backpack for extended periods of time may benefit from IMT.
Abstract Background Factors predicting quadriceps femoris muscle (QF) atrophy during the early period after arthroscopic ACL reconstruction have not been extensively studied. It is also yet to be ...confirmed whether muscle atrophy is a key determinant of postoperative QF weakness. Methods Mean changes in QF volume, MVIC torque and isometric endurance time were analysed in 25 patients prior to and at four and 12 weeks after surgery. A multivariable regression model of change in QF volume was made from combination of several parameters of preoperative QF size and strength and postoperative joint recovery. The impact of QF atrophy on muscle weakness was evaluated with univariate regression and MVIC torque to volume ratio at postoperative week only. Results The model of QF volume change was significant (P < 0.01) only at postoperative week 4, explaining 57% of its variation, where isometric endurance time had a negative and knee extension ROM deficit a positive weight. Change in QF volume explained (P < 0.05) 46% of the MVIC torque variation at postoperative week 12. A significant change (P < 0.05) in QF MVIC torque to volume ratio was observed at postoperative week 12. Conclusions Good prediction of QF atrophy in the first postoperative month can be made from studied variables, with isometric endurance and knee extension ROM deficit being the most significant contributors. The atrophy explained a large part of QF muscle weakness, whereas factors contributing to the remaining portion need further research.
Chronic pain is the most common cause of impaired work ability and thus represents a significant social and economic burden. STarT Back Screening Tool (SBT) is the most often used screening tool for ...rapid identification and classification of patients for their risk of development of chronic low back pain, which is valid and reliable in the original English version and translation into other languages. The aim of the present study was to translate the SBT into Slovenian and to evaluate its content validity and reliability. We translated the SBT from English into Slovenian and back according to the standard protocol. We tested its metric properties on a group of patients with low back pain aged 18 to 65 years. The reliability of the reassessment was calculated using the ICC and specific agreement, while the content validity of the questionnaire was determined using the ceiling and floor effect. Of the 42 patients who participated in the study, 42.9% were at low risk, 33.3% were at moderate risk, and 23.8% were at high risk of developing chronic pain, according to the SBT. The ICC for the entire sample was 0.96 (95% CI 0.92–0.98). The Slovenian translation of the SBT showed excellent specific agreement between the initial and repeat assessments: 91.4% for the low-risk group, 85.7% for the moderate-risk group, and 95.2% for the high-risk group. In addition, it showed good content validity, as no ceiling or floor effects were detected. The Slovenian translation of the questionnaire is suitable for clinical use.
Purpose
To evaluate predicting factors for patient-reported outcomes and revision interventions following surgical treatment of patients with patellofemoral instability.
Methods
From a prospective ...database at the university Orthopedic Department, 138 knees from 116 patients who underwent patellofemoral instability surgery (2012–2019) were enrolled in a retrospective analysis: 34 cases of isolated MPFLrec; 92 cases of MPFLrec plus tibial tuberosity transfer; and 12 cases of MPFLrec plus trochleoplasty. Patient-reported outcome measures were recorded for knee-specific function (KOOS), general quality of life (EQ-5D), and activity level (Tegner scale). Post-operative revision interventions were also actively recorded. As potential predicting factors, patient demographic (gender, age, BMI) and radiographic (pre-operative: patellar height and tilt, tibial tuberosity–trochlear groove distance, trochlear dysplasia, knee osteoarthritis; post-operative: MPFL insertion point; intra-operative: isolated vs. combined procedures, chondropenia severity score) parameters were analyzed using multivariate linear regression models.
Results
With median follow-up of 4.4 (1.0–8.9) years, all patient-reported outcome measures had significantly improved from pre-operative levels: KOOS cumulative, from 71 (15) to 78 (16); EQ-5D, from 0.68 (0.20) to 0.78 (0.21); and Tegner activity scale, from 3 (0–10) to 4 (0–10). No patellofemoral instability revision procedures were performed. One-fifth (27/138) of the operated knees required second surgical interventions, predominately due to hardware or arthrofibrosis. Patients who required post-operative knee manipulation under anesthesia or arthroscopic debridement showed lower post-operative improvement for KOOS cumulative and EQ-5D. Age, BMI, patellofemoral knee osteoarthritis, and shorter follow-up time revealed significant negative correlations to some of the post-operative KOOS subscales. Age was negatively correlated to post-operative EQ-5D, while post-operative Tegner activity scale was negatively correlated to female gender and patellofemoral chondropenia severity score. Femoral MPFL insertion point revealed no association with any outcome measures.
Conclusion
Patellofemoral instability surgery for isolated or combined MPFLrec is safe and substantially improves knee function and patient quality of life and activity levels. Serious adverse events are rare, with no recurrent patellofemoral instability. Patients who required post-operative knee manipulation or arthroscopic debridement showed less improvement in subjective measures of treatment outcomes. Older age, higher BMI, worse pre-operative patellofemoral cartilage status, and female gender had negative effects on outcome.
Level of evidence
III.
BACKGROUND: Postactivation potentiation (PAP) enhances contractility of skeletal muscle whereas fatigue deteriorates it. Available evidence suggests that the two phenomena may express differently in ...endurance and power athletes. OBJECTIVE: To compare the patterns of change in knee muscle contractility induced by PAP and fatigue between endurance and power athletes. METHODS: Eleven endurance and ten power athletes (age: 18–33 years) performed isokinetic fatigue and isometric PAP protocols with knee extensors and flexors on computerised dynamometer. Tensiomyography (TMG) of the vastus medialis and semitendinosus muscle medialis was performed before the protocols and during a 10-min recovery. RESULTS: The changes in TMG profile were most pronounced in the vastus medialis of power athletes following the PAP protocol and least pronounced in the semitendinosus of the endurance athletes following the fatigue protocol. The differences between athlete types were most significant for the time-domain TMG parameters of vastus medialis. A significant correlation (r= 0.51–0.73) between the fatigue indices and changes in TMG parameters was observed for the vastus medialis muscle only. CONCLUSIONS: The results show that the TMG patterns of PAP and fatigue in the vastus muscle differ between endurance and power athletes. In this muscle, the changes in TMG parameters are also strongly associated with the degree of fatigue.
BACKGROUND: Hand-held dynamometry (HHD) is used to assess muscle strength in various patient populations, but many variations in protocols exist. OBJECTIVE: First, to systematically develop a ...protocol of HHD for all lower limb muscle groups and evaluate intra-rater reliability; second, to validate HHD with fixed dynamometry for the knee flexor and extensor muscles. METHODS: Thirty healthy young adults (women: men – 15:15) participated in two testing sessions. HHD of 12 lower limb muscle groups was performed in both sessions, while fixed dynamometry of knee muscle groups was performed only in the second session. RESULTS: The intra-rater reliability of HHD was good for five muscle groups and excellent for seven muscle groups (ICC3, k= 0.80–0.96). The criterion validity of HHD ranged from very good to excellent for the knee flexors (r= 0.77–0.89) and from good to very good for the knee extensors (r= 0.65–0.78). However, peak moment values for the knee extensor muscles were underestimated by 32% (p< 0.001). CONCLUSIONS: The proposed HHD protocol provides reliable and valid measurements of lower limb muscle isometric strength in healthy adults, which may also be used to test patients with mild muscle strength deficits. However, possible underestimation of absolute strength must be considered when interpreting the results of knee extensors or other large muscles.
Background
To investigate the influence of sport-specific activities on coronal axial alignment of the lower limbs in adolescent football and ice hockey players.
Methods
This cross-sectional study ...targeted healthy adolescent male football and ice hockey players with at least 3 years of sports participation. 90 football and 38 ice hockey players aged 12–16 years were divided into five age-matched subgroups. Coronal alignment of the lower limbs was determined by measuring the players' intercondylar or intermalleolar (ICD-IMD) distance with a custom-made calliper. In addition, their sports history was recorded. An age-matched comparison between the two sports groups was performed using the two-way model ANOVA and a multiple regression model for ICD-IMD was constructed. Results were additionally compared with age-matched data from the general population published in recent literature.
Results
A statistically significant increase in ICD-IMD values (
p
< 0.05) was found between 12 (football 0 mm; ice hockey − 64 mm) and 16 years (football 340 mm; ice hockey 310 mm) in both sports groups. Results of regression analysis of pooled group data showed that ICD-IMD has low positive correlation (r = 0.407; r
2
= 0.168;
p
< 0.05) with time of participation in sport, but no association with age of athletes at the start of their sport participation (r = − 0.018; r
2
= 0.000;
p
> 0.05). There were no statistically significant differences between the two groups at any time point. Both sports groups showed a significant increase in ICD-IMD values (mean 198 mm) after the age of 14 compared to the general population.
Conclusions
Participation in football and ice hockey is associated with a similar increase in ICD-IMD in the adolescent years in male athletes. The observed increase was higher in both groups of athletes than in their peers who do not regularly participate in sports.
Level of Evidence
Level 4 (case series).
ABSTRACTIpavec, M, Grapar Žargi, T, Jelenc, J, and Kacin, A. Efficiency of pneumatic tourniquet cuff with asymmetric pressure distribution at rest and during isometric muscle action. J Strength Cond ...Res 33(9)2570–2578, 2019—The aim of this study was to compare effects of newly designed double-chamber cuff with asymmetric pressure (APC) distribution and standard single-chamber cuff with symmetric pressure (SPC) distribution on muscle perfusion and volitional activation. First, the 2 cuffs were compared bilaterally on resting thigh muscles of 17 healthy volunteers at 4 cuff pressures (120, 160, 200, and 240 mm Hg). Then, the subjects performed the isometric endurance test of knee extensor muscles to volitional failure at 40% of maximal volitional isometric action in both free-flow and blood flow restricted condition. Changes in hemoglobin kinetics in vastus lateralis muscle (near-infrared spectroscopy), surface electromyography of vastus medialis muscle, and pain intensity (visual analogue scale VAS) were continuously recorded. At rest, a significant difference (p = 0.009) in velocity of change in total hemoglobin concentration was noted between the cuffs at 160 mm Hg (APC = 0.028 μM·s and SPC = 0.056 μM·s). The VAS scores significantly increased (p = 0.031) at pressures ≥200 mm Hg, with no difference between the cuffs. Duration of isometric action with blood flow restriction was 12% shorter (p = 0.003) than in free-flow condition, with no difference between the cuffs. There were no significant differences in muscle activation or hemoglobin kinetics between the exercise conditions or cuff types. The results show that APC reduces blood flow in quadriceps femoris muscle at rest at lower pressure than SPC, which suggests its enhanced efficiency for blood flow restriction. Given that application of either type of cuff during sustained isometric action had only minor impact on muscle endurance and oxygen kinetics, future research must focus primarily on dynamic muscle actions.
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