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PubMed2005

The effects of a 12-week strength-training program on strength and functionality in women with fibromyalgia.

OBJECTIVE: To determine whether women with fibromyalgia benefit from strength training. DESIGN: Randomized controlled trial. SETTING: Testing was completed at the university and training was completed at a local community wellness facility. PARTICIPANTS: Twenty-nine women (age range, 18-54 y) with fibromyalgia participated. Subjects were randomly assigned to a control (n=14; wait-listed for exercise) or strength (n=15) group. After the first 4 weeks, 7 (47%) women dropped from the strength group. INTERVENTION: Subjects underwent 12 weeks of training on 11 exercises, 2 times a week, performing 1 set of 8 to 12 repetitions at 40% to 60% of their maximal lifts and were progressed to 60% to 80%. MAIN OUTCOME MEASURES: Subjects were measured for strength, functionality, tender point sensitivity, and fibromyalgia impact. RESULTS: The strength group significantly (P< or =.05) improved upper- (strength, 39+/-11 to 42+/-12 kg; control, 38+/-13 to 38+/-12 kg) and lower- (strength, 68+/-28 to 82+/-25 kg; control, 61+/-25 to 61+/-26 kg) body strength. Upper-body functionality measured by the Continuous-Scale Physical Functional Performance test improved significantly (strength, 44+/-11 to 50+/-16U; control, 51+/-11 to 49+/-13U) after training. Tender point sensitivity and fibromyalgia impact did not change. CONCLUSIONS: Strength training improved strength and some functionality in women with fibromyalgia. Interventions with resistance have important implications on independence and quality of life issues for women with fibromyalgia.

Activities of Daily Living↗

PubMed2005

Maturity- and sex-related changes in tibial bone geometry, strength and bone-muscle strength indices during growth: a 20-month pQCT study.

During growth, bone strength is conferred through subtle adaptations in bone mass and geometry in response to muscle forces. Few studies have examined the changes in bone geometry, strength and the bone-muscle strength relationship across maturity in boys and girls. Our aims were to describe (i) 20-month changes in bone geometry and strength at the tibial midshaft across three maturity groups of boys and girls, (ii) differences in these adaptations between sexes at the same approximate level of maturity and (iii) the bone-muscle strength relationship across maturity groups of boys and girls and between sexes. We used peripheral quantitative computed tomography (pQCT, Stratec XCT-2000) to measure change in total bone cross-sectional area (ToA, mm(2)), cortical area (CoA, mm(2)), average cortical thickness (C.Th., mm), section modulus (mm(3)) and muscle cross-sectional area (mm(2)) at the tibial midshaft (50% site) in 128 EARLY-, PERI- and POST-pubertal girls (n = 69, 11.9 +/- 0.6 years) and boys (n = 59, 12.0 +/- 0.6 years) across 20 months. We also calculated two bone-muscle strength indices (BMSI) for compression (CoA/MCSA) and bending [strength index/MCSA; where strength index = Z / (tibial length / 2)]. EARLY boys and girls had smaller ToA at baseline than same sex PERI or POST participants. There were no sex differences in ToA or CoA at baseline; however, boys increased both parameters significantly more than girls in every maturity group (8.5-11.1%, P < 0.01). These changes in bone geometry conferred greater gains in bone strength for boys compared with girls in each maturity group (13.8-15.6%, P < 0.01). Baseline BMSIs did not differ between sexes for EARLY and PERI groups, whereas BMSIs were significantly higher for POST boys compared with POST girls (P < 0.05). BMSIs decreased for EARLY and PERI girls (-7.4-(-1.1%)) whereas the ratios remained stable for EARLY and PERI boys (-0.6-2.5%). This sex difference in BMSI change was due to a relatively greater increase in CoA among EARLY and PERI boys compared with same-maturity girls. BMSIs remained stable in POST girls and decreased in POST boys due to relatively greater gains in MCSA. This study provides novel longitudinal descriptions of the maturity- and sex-specific changes in bone geometry, strength and bone-muscle strength indices.

Adolescent↗

PubMed2003

Shear punch strength and flexural strength of model composites with varying filler volume fraction, particle size and silanation.

OBJECTIVE: The effect of filler volume fraction, particle size and silanation on shear punch strength, flexural strength and flexural modulus of model composites has been evaluated. METHODS: Hybrid type glass filled (0-65.2 vol%), composites some without filler silanation (30.7-51.0 vol%) and microfilled type (0-13.0 vol%) resin matrix (UDMA and EGDMA) composites (Shofu Inc., Japan) were used in the study. For the shear punch test, 10 disc specimens, 0.5mm thick and 9 mm diameter, were prepared for each composite and tested with a 3.2mm dia punch at 1.0mm/min. Flexural strength (n=10) was measured by the method outlined in ISO 4049. Data were analyzed using ANOVA and Fisher's multiple-range test. RESULTS: Shear punch strength and flexural strength increased with increasing filler content up to 52.2% for hybrid composites and between 0 and 9.1% for microfilled composites. Shear punch strength and flexural strength decreased with increasing filler volume fraction for un-silanated composites. Flexural modulus for all materials increased with increasing filler volume fraction. Hybrid composites with silanated fillers have significantly higher values of flexural strength, flexural modulus and shear punch strength than equivalent materials with un-silanated fillers. SIGNIFICANCE: The results showed that filler silanation is an important factor for determining material strength. Additions of small quantities of microfillers appeared to have a greater effect on shear strength than equivalent amounts of hybrid filler. The shear punch test may prove beneficial for routine testing of composites as specimen preparation was simple, specimen quality was easy to maintain and the results are meaningful.

Analysis of Variance↗

PubMedDate not supplied

Digit ratio and hand-grip strength in German and Mizos men: cross-cultural evidence for an organizing effect of prenatal testosterone on strength.

The ratio of the length of the second and fourth digits (2D:4D), a putative proxy of prenatal testosterone (PT), is correlated with measures of physical fitness. The relationship between the organizing effect of PT on physical fitness is likely to arise as a response to intrasexual male competition for females. Physical strength is also likely to be important in intrasexual conflict, but nothing is known concerning the relationship between 2D:4D and strength. The strength of an individual is strongly influenced by body size, and 2D:4D is strongly dependent on ethnicity. We present evidence that strength, as measured from hand-grip strength, is related to 2D:4D in samples from two ethnic groups (52 Caucasian men from Germany, and 88 Oriental Mizos men from northeast India) which differed markedly in size. We found that 1) the German men were heavier and stronger, but had higher 2D:4D (lower PT) than the Mizos men; 2) a median split for grip strength into low (LGS) and high (HGS) groups showed that for right-hand 2D:4D (but not left-hand 2D:4D), the LGS men had higher 2D:4D than the HGS men; and 3) the relationships between right 2D:4D and grip strength were independent of ethnicity, age, height, and weight. Measures of grip strength correlate strongly with strength in other muscle groups, so we conclude that PT may have an early organizing effect on strength in men, and this is likely to be widespread in human groups.

Adult↗

PubMed2004

Isometric pull-push strengths in workspace: 1. Strength profiles.

The isometric pull and push strength profiles of males and females were determined in seated and standing positions in the workspace. The strongest pull strength location was at extreme reach vertically above the shoulder for both males and females. The greatest pull strength of 400 Newtons (N) for males was recorded in the seated and standing positions. Females' pull strengths in the seated and standing positions were 222 and 244 N, respectively. The strongest push strength was always at the maximum reach at the overhead location. Males' maximum push strength was 227 N in the seated position and 251 N in the standing position. Females' maximum push strength was 96 N in the seated position and 140 N in the standing position. On the average the strength in the standing position was 79% of the seated position. The push strength was 71% of the pull strength and females were 56% as strong as males.

Adult↗

PubMed2004

Handgrip strength, pulmonary function tests, and pulmonary muscle strength in fibromyalgia syndrome: is there any relationship?

OBJECTIVE: It has been reported that patients with fibromyalgia syndrome (FMS) have lower maximal respiratory pressures than healthy subjects, indicating reduced pulmonary muscle strength. It has also been reported that patients with FMS have reduced grip strength. In this study, we aimed to examine the possible relationship between handgrip strength as a determinant of peripheral muscle strength and pulmonary muscle strength in patients with FMS by comparing them with healthy controls. METHODS: Forty-one consecutive women with FMS (diagnosed according to the American College of Rheumatology 1990 criteria) were compared with 40 age- and body mass index-matched healthy female controls. Pulmonary function tests were assessed by spirometry. Maximal pulmonary pressures were evaluated using an oral pressure meter. A dyspnea score was obtained. Pain was scored according to visual analogue scale and chest pain was classified (0-9) in fibromyalgia patients. Chest expansion was also measured in the two groups. Tender points were also evaluated in FMS patients. Grip strength (Jamar handheld dynamometer) was also measured in the two groups. RESULTS: The difference in pulmonary function tests was not statistically significant between groups. Maximal respiratory pressures (maximum inspiratory pressure and maximum expiratory pressure) and endurance (maximum ventilatory volume) were significantly lower in patients with FMS than in controls. There was also a statistically significant difference between groups regarding grip strength. There was also significant correlation between maximal inspiratory pressure and maximal expiratory pressure values and handgrip strength in patients with FMS. CONCLUSION: These data indicate that handgrip strength may be a determinant of pulmonary muscle strength in fibromyalgia patients.

Adult↗

PubMed2006

Task-oriented progressive resistance strength training improves muscle strength and functional performance in individuals with stroke.

OBJECTIVE: To examine the effectiveness of task-oriented progressive resistance strength training on lower extremity strength and functional performance in chronic stroke subjects. DESIGN: Single-blind, randomized controlled trial. SETTING: Medical centre and district hospital. SUBJECTS: Forty-eight subjects at least one year post stroke. INTERVENTIONS: Participants randomly allocated to two groups, control (n-/24) and experimental (n-/24). Subjects in the control group did not receive any rehabilitation training. Subjects in the experimental group were put on a four-week task-oriented progressive resistance strength training. MAIN MEASURES: Lower extremity muscle strength, gait velocity, cadence, stride length, six-minute walk test, step test, and timed up and go test. RESULTS: Muscle strength significantly improved in the experimental group for strong side muscle groups (ranged from 23.9% to 36.5%) and paretic side muscle groups (ranged from 10.1% to 77.9%). In the control group muscle strength changes ranged from 6.7% gain to 11.2% decline. The experimental group showed significant improvement in all selected measures of functional performance except for the step test. In the control group, the number of repetitions of the step test significantly decreased (-20.3%) with no change in other functional tests. There was a significant difference between groups for muscle strength and all functional measures. The strength gain was significantly associated with gain in the functional tests. CONCLUSIONS: The task-oriented progressive resistance strength training programme could improve lower extremity muscle strength in individuals with chronic stroke and could carry over into improvement in functional abilities.

Aged↗

PubMed2003

[The measurement and comparison of shear fracture strength and shear bond strength between carbon fiber post and some other posts].

OBJECTIVE: The shear fracture strengths of carbon fiber post, IPS-Empress 2 all-ceramic post (without ZrO2 post), cast Ni-Cr alloy post, prefabricated zirconia ceramic post, human dentin and the shear bonding strengths of the first three kinds of post bonded in the human root canals were measured and compared, which are as the reference for dental clinic. METHODS: Standard cylindrical samples were made respectively in each group of carbon fiber post, IPS-Empress 2 all-ceramic post, cast Ni-Cr alloy post, prefabricated zirconia ceramic post, human dentin, three for each group. The shear fracture strengths of these samples were measured by universal testing machine (AUTOGRAPH DCS5000). Standard cylindrical samples were made respectively in each group of carbon fiber post, IPS-Empress 2 all-ceramic post (without ZrO2 post), cast Ni-Cr alloy post, five for each group. They were bonded in extracted human root canals that had been prepared to 3.0 mm length and 2.0 mm diameter with Glass ionomer cement (Japan Shofu). The shear bond strengths were measured by the same universal testing machine. RESULTS: The shear fracture strengths of the carbon fiber post (199MPa), cast Ni-Cr alloy post (210MPa, shear bend strength) and prefabricated zirconia ceramic post (193MPa) were statistically higher than those of IPS-Empress 2 all-ceramic post (109MPa) and human dentin (100MPa). The shear fracture strength of the carbon fiber post was statistically similar to that of cast Ni-Cr alloy post and prefabricated zirconia ceramic post. There were no statistical differences between the shear bond strengths of carbon fiber post (2.4MPa) and cast Ni-Cr alloy post (3.8MPa). IPS-Empress 2 all-ceramic post broke before debonding (2.7, break value). CONCLUSIONS: Carbon fiber post, as well as cast Ni-Cr alloy post and prefabricated zirconia ceramic post, has a comparatively high shear fracture strength. The shear bond strengths of carbon fiber post is similar to cast Ni-Cr alloy post.

Carbon↗

PubMed2002

Relationship between the strength of glass ionomers and their adhesive strength to metals.

OBJECTIVES: The objective of this study was to examine the possible correlation between the strength of glass ionomers and their adhesive strength to metals. METHODS: Three different brands of glass ionomers mixed at four different P/L ratios were evaluated. The compressive and diametral tensile strengths of the cements were determined. The shear bond strengths were determined between four different types of dental casting alloys and the cement made with the different P/L ratios. RESULTS: Significant (p < 0.05) increases in the bond strength to any of the metal surfaces were found in the cement specimens mixed at the highest P/L ratio compared to those mixed at the lowest P/L ratio. For two glass ionomers (FI and DNT), the specimens prepared at the highest P/L ratio showed significantly greater diametral tensile strength than those prepared at the lowest P/L ratio (p < 0.05). SIGNIFICANCE: The present study showed a significant correlation between diametral tensile strengths and bond strengths. It is suggested that the use of glass ionomers with high mechanical strength is an important factor of enhancing the adhesion to metal surfaces.

Adhesiveness↗

PubMed2004

Effect of a 10-week strength training program and recovery drink on body composition, muscular strength and endurance, and anaerobic power and capacity.

OBJECTIVE: We investigated whether postexercise consumption of a supplement containing whey protein, amino acids, creatine, and carbohydrate combined with a strength training program promotes greater gains in fat-free mass (FFM), muscle strength and endurance, and anaerobic performance compared with an isocaloric, carbohydrate-only control drink combined with strength training. METHODS: The study was double blind and randomized, and the experimental supplement was compared with a carbohydrate-only control. Forty-one males (n = 20 in control group, n = 21 in the supplement group; mean age, 22.2 y) participated in a 4 d/wk, 10-wk periodized strength training program. Subjects had to complete at least 70% of the workouts. Before and after 10 wk of strength training, subjects were tested for body composition by using hydrostatic weighing and skinfold thicknesses, one repetition maximum strength and muscular endurance for the bench press and 45-degree leg press, and anaerobic performance using a 30-s Wingate test. Thirty-three subjects (80.5%) completed the training program (n = 15 in control group, n = 18 in the supplement); these 33 subjects also completed all post-training test procedures. Data were analyzed with two-way analysis of variance with repeated measures on time. P <== 0.05 was set as statistically significant. All statistical analyses, including calculation of effect size and power, were completed with SPSS 11.0. RESULTS: Across groups, FFM increased during 10 wk of strength training. Although there was no statistically significant time x group interaction for FFM, there was a trend toward a greater increase in FFM for the supplement group (+3.4 kg) compared with the control group (+1.5 kg; P = 0.077). The effect size (eta(2) = 0.100) was moderately large. Percentage of body fat declined and fat mass was unchanged; there were no differences between groups. One repetition maximum strength for the bench press and 45-degree leg press increased, but there were no differences between groups. Muscular endurance expressed as the number of repetitions completed with 85% of the one repetition maximum was unchanged; external work, which was estimated as repetitions completed x resistance used, increased for the 45-degree leg press but not for the bench press over the 10-wk training period; there were no time x group interactions for either measurement. Anaerobic power and capacity improved, but there were no differences between groups for these variables or for fatigue rate. CONCLUSIONS: Consumption of a recovery drink after strength training workouts did not promote greater gains in FFM compared with consumption of a carbohydrate-only drink; however, a trend toward a greater increase in FFM in the supplement group suggests the need for longer-term studies. Performance variables such as muscle strength and endurance and anaerobic performance were not improved when compared with the carbohydrate-only group.

Adolescent↗

PubMed2003

Comparison of high-field-strength versus low-field-strength MRI of the shoulder.

OBJECTIVE: Previous studies have reported similar results of shoulder MRI versus arthroscopy for high-field-strength (1.5-T) and low-field-strength (0.2-T) units. We report our experience with the accuracy of high- versus low-field-strength units versus arthroscopy for detection of supraspinatus tendon tears and labral tears in the same patients. SUBJECTS AND METHODS. Three musculoskeletal radiologists prospectively interpreted shoulder MRIs from 40 patients who had a complete shoulder MRI examination on a 0.2-T system and limited imaging on a 1.5-T unit. Proton-density axial and fat-saturated T2-weighted coronal and sagittal sequences were performed. Each radiologist interpreted the open unit images first and the high-field-strength images second. Results from 28 patients who also underwent arthroscopy were also compared with the MRI interpretations. All scans were then retrospectively reinterpreted by consensus of the three reviewers, who were unaware of the patient's name, results of previous MRI, or arthroscopy report (if any). RESULTS: High-field-strength images altered reviewers' interpretations of low-field-strength scans for nine of 40 patients. In four patients, full-thickness supraspinatus tendon tears could be diagnosed definitively on the high-field-strength unit but not on the open unit. Three labral tears and two superior labral anteroposterior lesions could be depicted definitively on the high-field-strength unit but not on the open unit. All tears were confirmed at arthroscopy. CONCLUSION: High-field-strength MRI units provide better spatial and contrast resolution and allow more accurate interpretations than low-field-strength units; these findings may affect clinical treatment.

Arthroscopy↗

PubMed1996

Influence of muscle strength on bone strength during childhood and adolescence.

In connection with the prevention of osteoporosis, paediatrics is challenged with ensuring the optimal formation of the skeletal system with maximal bone strength during childhood and youth. Biomechanical use represents the most important stimulus for activating the skeletal system. The measurement of muscle strength (grip strength) in 97 females aged 3-62 years and 71 males aged 3-61 years showed an age-dependent course. On the whole, males have greater strength with a more pronounced increase after puberty, reaching a peak maximum at 25-30 years. Females show a more moderate increase after puberty. In a pilot study, bone strength (as bone strength index-BSI) was analysed at the distal radius using peripheral quantitative computerized tomography (pQCT). BSI was calculated on the basis of the geometric data of the polar moment of resistance in combination with the cortical bone density. BSI values increase with age and reach a peak maximum at 25-30 years. There was a highly significant correlation between BSI and grip strength (r = 0.87). These relationships are especially interesting for therapeutic concepts differentiating between direct and indirect (via the muscle system) influences on the skeletal system. The non-invasive bone strength analysis in combination with muscle strength offer new perspectives for the evaluation of the functional muscle-bone unit.

Adolescent↗

PubMed2006

Adaptations in upper-body maximal strength and power output resulting from long-term resistance training in experienced strength-power athletes.

The purpose of this investigation was to observe changes in maximal upper-body strength and power and shifts in the load-power curve across a multiyear period in experienced resistance trainers. Twelve professional rugby league players who regularly performed combined maximal strength and power training were observed across a 4-year period with test data reported every 2 years (years 1998, 2000, and 2002). Upper-body strength was assessed by the 1 repetition maximum bench press and maximum power during bench press throws (BT Pmax) with various barbell resistances of 40-80 kg. During the initial testing, players also were identified as elite (n = 6) or subelite (n = 6), depending upon whether they participated in the elite first-division national league or second-division league. This subgrouping allowed for a comparison of the scope of changes dependent upon initial strength and training experience. The subelite group was significantly younger, less strong, and less powerful than the elite group, but no other difference existed in height or body mass in 1998. Across the 4-year period, significant increases in strength occurred for the group as a whole and larger increases were observed for the subelite than the elite group, verifying the limited scope that exists for strength gain in more experienced, elite resistance-trained athletes. A similar trend occurred for changes in BT Pmax. This long-term observation confirms that the rate of progress in strength and power development diminishes with increased strength levels and resistance training experience. Furthermore, it also indicates that strength and power can still be increased despite a high volume of concurrent resistance and endurance training.

Adaptation, Physiological↗

PubMed1999

Dynamic strength training in patients with early rheumatoid arthritis increases muscle strength but not bone mineral density.

OBJECTIVE: To assess the effects of 12 months' dynamic strength training on muscle strength and bone mineral density (BMD) at the lumbar spine and femoral neck in patients with early rheumatoid arthritis (RA). METHODS: Thirty-two subjects in the training group (EG) and 33 in the control group (CG) completed the study. EG carried out strength training 2 times a week with moderate loads of 50-70% of repetition maximum. They were also encouraged to do recreational physical activities. CG performed recreational physical activities and range of motion exercises. Maximal strength of the knee extensors, trunk extensors and flexors, and grip strength were recorded with dynamometers. BMD was measured using dual x-ray absorptiometry. Modified Disease Activity Score, erythrocyte sedimentation rate, and pain were used for the estimation of disease activity, and Stanford Health Assessment Questionnaire to measure functional disability. RESULTS: The 12 month resistance training in EG led to statistically significant mean increases of 22-35% in all muscle groups examined. CG patients were also able to increase their strength to some degree (3-24%), but at the end of the study strengths in CG were significantly lower than in EG. By the end of the study lumbar spine BMD had changed by +0.19% (4.24) in EG and by -1.14% (4.36) in CG. The corresponding changes of femoral BMD were +1.10% (3.71) and -0.03% (3.58). The changes in BMD were minor and statistically not significant in both groups. However, femoral BMD was found to be decreased among those patients treated periodically with oral glucocorticoids (n = 15, 3 subjects from EG and 12 from CG) compared with changes in BMD among those not treated with systemic glucocorticoids (n = 50). CONCLUSION: Minimally supervised strength training resulted in significant improvements in muscle strength without detrimental effects on disease activity. The detected annual changes in central BMD were minor and statistically insignificant in both groups. Special attention should be focused on those patients with RA with high disease activity and concomitant glucocorticoid treatment.

Arthritis, Rheumatoid↗

PubMed1995

Isometric and isokinetic quadriceps strength in gonarthrosis; inter-relations between quadriceps strength, walking ability, radiology, subchondral bone density and pain.

Patients with osteoarthrosis suffer from disability and pain. We measured isokinetic and isometric peak torque in 20 women with gonarthrosis (GA) and in 26 healthy controls. Relationships between muscle strength, walking and stair climbing time, pain level and pain disability scores as assessed by the patients using an extensive questionnaire, radiological changes and subchondral sclerosis expressed as bone mineral density (BMD, g/cm2) of the proximal tibia were studied. Precision errors of the torque measurements in both GA patients and controls were approximately 6%. In the GA patients, isokinetic and isometric quadriceps strength was reduced by 40 and 15% (p < 0.01) respectively, and walking and stair climbing time was increased by 30% (p < 0.005). Isokinetic strength was a better predictor of pain level and pain disability scores than isometric strength and radiological stage. Walking time and stair climbing time were not associated with quadriceps strength, pain level, pain disability scores or radiological changes. Subchondral BMD was not predictive of pain. The study suggests that quadriceps strength assessed by isokinetic dynamometry in GA is a reliable measurement. Isokinetic strength was pronouncedly reduced compared to isometric strength and was a more important predictor of pain and pain disability than isometric strength. These findings should be taken into consideration when planning exercise studies and programmes in GA.

Aged↗

PubMed2002

Neuromuscular adaptations during concurrent strength and endurance training versus strength training.

The purpose of this study was to investigate effects of concurrent strength and endurance training (SE) (2 plus 2 days a week) versus strength training only (S) (2 days a week) in men [SE: n=11; 38 (5) years, S: n=16; 37 (5) years] over a training period of 21 weeks. The resistance training program addressed both maximal and explosive strength components. EMG, maximal isometric force, 1 RM strength, and rate of force development (RFD) of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) throughout the lengths of 4/15-12/15 (L(f)) of the femur, muscle fibre proportion and areas of types I, IIa, and IIb of the vastus lateralis (VL), and maximal oxygen uptake (VO(2max)) were evaluated. No changes occurred in strength during the 1-week control period, while after the 21-week training period increases of 21% (p<0.001) and 22% (p<0.001), and of 22% (p<0.001) and 21% (p<0.001) took place in the 1RM load and maximal isometric force in S and SE, respectively. Increases of 26% (p<0.05) and 29% (p<0.001) occurred in the maximum iEMG of the VL in S and SE, respectively. The CSA of the QF increased throughout the length of the QF (from 4/15 to 12/15 L(f)) both in S (p<0.05-0.001) and SE (p<0.01-0.001). The mean fibre areas of types I, IIa and IIb increased after the training both in S (p<0.05 and 0.01) and SE (p<0.05 and p<0.01). S showed an increase in RFD (p<0.01), while no change occurred in SE. The average iEMG of the VL during the first 500 ms of the rapid isometric action increased (p<0.05-0.001) only in S. VO(2max) increased by 18.5% (p<0.001) in SE. The present data do not support the concept of the universal nature of the interference effect in strength development and muscle hypertrophy when strength training is performed concurrently with endurance training, and the training volume is diluted by a longer period of time with a low frequency of training. However, the present results suggest that even the low-frequency concurrent strength and endurance training leads to interference in explosive strength development mediated in part by the limitations of rapid voluntary neural activation of the trained muscles.

Adaptation, Physiological↗

PubMed1996

Muscular weakness assessment: use of normal isometric strength data. The National Isometric Muscle Strength (NIMS) Database Consortium.

OBJECTIVE: Assessment of muscle strength is vital to the management of patients with muscular weakness. Clinical interpretation of isometric strength data for individual patients has been limited because of the lack of a reference population for comparison. The purpose of this study was to develop regression equations to predict maximal isometric strength based on gender, age, height, and weight. Patients' absolute strength values may then be expressed as a percentage of their predicted values, facilitating the determination of presence and extent of weakness. DESIGN: Three separate neuromuscular research groups developed databases of normal maximal isometric strength values, using standardized testing procedures. The databases were combined into a single database, and multiple regression equations were formulated for strength prediction for the 20 muscle groups tested. SETTING: Seven neuromuscular research units, each within the neurology department of a university-based teaching facility. SUBJECTS: A convenience sample of 493 volunteers who had no medical conditions that would have prohibited them from performing a maximal isometric strength test. MAIN OUTCOME MEASURE: Maximal isometric strength (kg) of ten muscle groups was measured bilaterally. RESULTS: Regression equations and 95% prediction intervals are derived from the combined database. A case study demonstrates the use of the predictive equations in determining presence and extent of weakness. CONCLUSION: Predictive strength equations facilitate assessment of muscular weakness.

Adolescent↗

PubMed1998

Effects of strength training on strength development and joint position sense in functionally unstable ankles.

OBJECTIVE: To examine the effects of ankle-strengthening exercises on joint position sense and strength development in subjects with functionally unstable ankles. DESIGN AND SETTING: Subjects were randomly assigned to a training or control group. The training group participated in a 6-week strength-training protocol using rubber tubing 3 times a week throughout the training period. The control group did not participate in the strength-training protocol. SUBJECTS: Twenty healthy college students (10 females, 10 males, age = 20.6 +/- 2.23 years; ht = 176.40 +/- 7.14 cm; wt = 74.18 +/- 10.17 kg) with a history of functional ankle instability volunteered to participate in this study. MEASUREMENTS: We pretested and posttested dorsiflexor and evertor isometric strength with a handheld dynamometer and collected joint position sense (JPS) data at 20 degrees for inversion and plantar flexion and at 10 degrees for eversion and dorsiflexion. RESULTS: Statistical tests for strength and JPS revealed significant group-by-time interactions for dorsiflexion strength, eversion strength, inversion JPS, and plantar flexion JPS. Simple main-effects testing revealed improvements in training group strength and JPS at posttesting. There were no significant effects for eversion JPS, but the group main effect for dorsiflexion JPS was significant, with the experimental group having better scores than the control group. CONCLUSIONS: Ankle-strengthening exercises improved strength, inversion JPS, dorsiflexion JPS, and plantar flexion JPS in subjects with functionally unstable ankles.

Journal Article↗