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PubMed2002

Predicting human vertebral bone strength by vertebral static histomorphometry.

The study investigates the relationship between static histomorphometry and bone strength of human lumbar vertebral bone. The ability of vertebral histomorphometry to predict vertebral bone strength was compared with that of vertebral densitometry, and also with histomorphometry and bone strength of iliac crest bone biopsies. The material comprised matched sets of second lumbar vertebrae, third lumbar vertebrae, and two iliac crest bone biopsies from each of 21 women (19--96 years) and 24 men (23--95 years). One of the iliac crest biopsies and 9-mm-thick mediolateral slices of half of each of the entire vertebral bodies (L-2) were used for histomorphometry. The other iliac crest biopsies and the L-3 were destructively tested by compression. High correlation was found between BV/TV or Tb.Sp and vertebral bone strength (absolute value of r = 0.86 in both cases). Addition of Tb.Th significantly improved the correlation between BV/TV and bone strength, and the addition of bone space star volume significantly improved the correlation between Tb.Sp and bone strength (from absolute value of r = 0.86 to absolute value of r = 0.89 in both cases). Bone structure (connectivity density) was not capable of improving the prediction of bone strength of the vertebral body. The correlations between BV/TV of L-2 and bone strength of L-3 were comparable with the correlation obtained by quantitative computed tomography (QCT), peripheral QCT (pQCT), and dual-energy X-ray absorptrometry (DEXA) of L-3 and bone strength of L-3. The iliac crest was found to have low predictive power of vertebral bone strength (iliac BV/TV: r = 0.62; iliac bone strength: r = 0.67). No gender-related differences were found in any of the relationships. It was shown that trabecular bone volume BV/TV and mean trabecular plate separation Tb.Sp are good predictors of vertebral bone strength. The ability of histomorphometry to predict vertebral bone strength was comparable to that of densitometry. Bone structure assessed by connectivity density did not improve the correlation between static histomorphometric measures and vertebral bone strength. No gender-related differences were found in any of the relationships. Neither static histomorphometry nor biomechanical testing of iliac crest bone biopsies is a good predictor of vertebral bone strength.

Adolescent↗

PubMed2000

Effect of implant design and endplate preparation on the compressive strength of interbody fusion constructs.

STUDY DESIGN: A human cadaveric study on the compressive strength of different lumbar interbody fusion implants and endplate preparation techniques was performed. OBJECTIVES: To assess the axial compressive strength of an implant with peripheral endplate contact as opposed to full surface contact, and to assess whether removal of the central bony endplate affects the axial compressive strength. SUMMARY OF BACKGROUND DATA: The compressive strength of interbody fusion constructs has been compared between implants and bone grafts. Neither implant design nor endplate preparation has been shown to affect strength. Removal of the central bony endplate for bone grafts was noted to improve graft incorporation but also to facilitate subsidence. METHODS: A total of 44 vertebrae were tested in four experimental groups by combining two interbody implants (full-surface vs peripheral surface support) with two endplate preparation techniques (intact bony endplate vs removal of the central bony endplate). Specimens were tested to ultimate compressive failure using a 50 N/second ramped load. Yield strength and ultimate compressive strength were compared between groups using two-factor analysis of covariance. A P value less than 0.05 was considered significant. Stepwise linear regressions assessed the predictive power of age, bone mineral content, and the implant's normalized endplate coverage on yield strength and ultimate compressive strength. RESULTS: Neither implant design nor endplate preparation technique affected yield strength or ultimate compressive strength. Age, bone mineral content, and the normalized endplate coverage were strong predictors of yield strength (P < 0. 0001; r2 = 0.459) and ultimate compressive strength (P < 0.0001; r2 = 0.510). CONCLUSIONS: An implant with only peripheral support resting on the apophyseal ring offers axial mechanical strength similar to that of an implant with full support. Neither supplementary struts nor a solid implant face has any additional mechanical advantage, but reduces graft-host contact area. Removal of the central bony endplate is recommended because it does not affect the compressive strength and promotes graft incorporation.

Adolescent↗

PubMed2007

Effects of teriparatide and alendronate on vertebral strength as assessed by finite element modeling of QCT scans in women with osteoporosis.

UNLABELLED: FE modeling was used to estimate the biomechanical effects of teriparatide and alendronate on lumbar vertebrae. Both treatments enhanced predicted vertebral strength by increasing average density. This effect was more pronounced for teriparatide, which further increased predicted vertebral strength by altering the distribution of density within the vertebra, preferentially increasing the strength of the trabecular compartment. INTRODUCTION: Teriparatide 20 microg/day (TPTD) and alendronate 10 mg/day (ALN) increase areal, measured by DXA, and volumetric, measured by QCT, lumbar spine BMD through opposite effects on bone remodeling. Using finite element (FE) modeling of QCT scans, we sought to compare the vertebral strength characteristics in TPTD- and ALN-treated patients. MATERIALS AND METHODS: A subset of patients (N = 28 TPTD; N = 25 ALN) from the Forteo Alendronate Comparator Trial who had QCT scans of the spine at baseline and postbaseline were analyzed. The QCT scans were analyzed for compressive strength of the L(3) vertebra using FE modeling. In addition, using controlled parameter studies of the FE models, the effects of changes in density, density distribution, and geometry on strength were calculated, a strength:density ratio was determined, and a response to bending was also quantified. RESULTS: Both treatments had positive effects on predicted vertebral strength characteristics. At least 75% of the patients in each treatment group had increased strength of the vertebra at 6 months compared with baseline. Patients in both treatment groups had increased average volumetric density and increased strength in the trabecular bone, but the median percentage increases for these parameters were 5- to 12-fold greater for TPTD. Larger increases in the strength:density ratio were also observed for TPTD, and these were primarily attributed to preferential increases in trabecular strength. CONCLUSIONS: These results provide new insight into the effects of these treatments on estimated biomechanical properties of the vertebra. Both treatments positively affected predicted vertebral strength through their effects on average BMD, but the magnitudes of the effects were quite different. Teriparatide also affected vertebral strength by altering the distribution of density within the vertebra, so that overall, teriparatide had a 5-fold greater percentage increase in the strength:density ratio.

Aged↗

PubMed1990

[Influence of types and surface treatment of dental alloy and film thickness of cements on bond strength of dental luting cements].

The goal of this study was to test the influence of the type and oxidation treatment of dental casting alloys on the tensile bond strength of luting cements. Also, the influence of film thickness of luting cements on the tensile bond strength of different dental casting alloys was examined. Four different luting cements (zinc phosphate, polycarboxylate, glass ionomer and adhesive resin cements) and four different dental casting alloys (Au-Ag-Cu, Ag-Pd, hardened Ag-Pd and Ni-Cr alloys) were used. Cylindrical alloy rods for the tensile bond strength test were casted, and then, top surfaces of the rods were cemented with each luting cement to the bottom surfaces of other rods, using the film thickness adjustment apparatus. The film thickness of luting cement was adjusted to 20, 30, 50, 75 or 100 microns. The tensile bond strengths of each cement to different casting alloys at each film thickness were measured one day after the rods had been cemented. The tensile bond strength of the zinc phosphate cement could not be determined in this study due to the separation of the alloy rods cemented with the zinc phosphate cement in water before the tensile test. The tensile bond strength to the adhesive resin cement to any alloy showed the greatest strength; however, that of the glass ionomer cement to any alloy was the lowest strength among the cements examined. The Ni-Cr alloy had the highest bond strength of any luting cement, compared to other alloys. The tensile bond strengths of luting cements significantly decreased with the increase in film thickness of cement layer. The adhesive resin cement had the greatest bond strength, and the glass ionomer cement was the lowest bond strength at any film thickness. The oxidation treatment significantly increased the bond strength of the adhesive resin cement to both Au-Ag-Cu and Ag-Pd alloys. The tensile bond strength of the adhesive resin cement was most dependent upon the film thickness of cement layer, and that of the polycarboxylate cement was least dependent upon the film thickness of cement layer among the cements examined. In addition, the oxidation treatment for precious alloys could be a factor contributing to the increase in the bond strength of the adhesive resin cement.

Adhesiveness↗

PubMed2005

Relationship between leg bone mineral values and muscle strength in women with different physical activity.

This study examines whether knee extensor muscle isometric, isokinetic, and isoinertial strength values in women with different physical activity and body composition patterns are related to leg bone mineral density (BMD) and bone mineral content (BMC) values. A total of 129 women aged 17-40 participated in this study. They were divided into four groups: strength-trained (n = 33), endurance-trained (n = 32), normal weight sedentary (n = 41), and overweight sedentary (n = 23) women. In addition, the subjects were grouped as physically active (n = 65) or sedentary (n = 64) women. BMD and BMC for both legs (LBMD and LBMC, respectively) and for the dominant leg alone (DLBMC), body fat percentage and lean body mass (LBM), maximal knee extension isometric (ISOM) and isokinetic (ISOK) strength at the angular velocity of 60 deg.s(-1), and isoinertial leg explosive strengths (countermovement jump CMJ) were measured. In endurance-trained women, LBMD was dependent on body mass index (BMI) (33.7% of the variance, R2 x 100), and in the physically active group and the total group with LBM (14.6% and 15.6%, respectively). In the overweight group, LBMD was dependent on ISOK strength (21.7% of the variance, R2 x 100). In the sedentary and total groups, ISOM strength was more important (10.3% and 5.0%, respectively); in the strength-trained group, body weight influenced LBMC, accounting for 71.6% of the variance (R2 x 100). In the endurance-trained women, height influenced LMBC (37.9%, R2 x 100). In sedentary and overweight women, LBM accounted for 52.1% and 61.4% of the total variance in LBMC. In these groups, ISOM strength accounted for 15.3% and 25.9% of the variance in LBMC. In overweight women, ISOM and ISOK strength together influenced LBMC highly (64.8% of the variance, R2 x 100). In the sedentary group, the influence of LBM on LBMC was higher than in the active group (82.1% and 50.5% of the variance, respectively). In the total group, LBM influenced LBMC, accounting for 54.5% of the variance (R2 x 100). ISOM strength (22.7%) alone or in combination with ISOK strength (35.8%) and CMJ (41.7%) (R2 x 100) in LBMC in the sedentary group explained the variance. In the total group, ISOM strength alone (13.2%) or in combination with CMJ (17.1%) influenced LBMC (R2 x 100). Our results suggest that (1) muscle strength and anthropometrical parameters were associated with LBMD; (2) LBM and ISOM strength had a significant relationship with DLBMC and LBMC only in nonathletic women; and (3) strength measured with different regimens highly influenced LBMC compared with LBMD, especially in the sedentary groups.

Adolescent↗

PubMed1993

Evaluation of finite element analysis for prediction of the strength reduction due to metastatic lesions in the femoral neck.

Between 30 and 70% of almost one million new cancer patients diagnosed each year will develop osseous metastases. Clinicians are faced with the difficult task of determining which patients require prophylactic stabilization to prevent pathologic fracture. The objective of this study was to test the ability of macroscopic finite element models to predict the fracture strength of the proximal femur with a lesion in the femoral neck. Drill hole defects in human cadaver femora were used to simulate lesions that penetrate one cortex of the femoral neck. Based on the first of two series of in vitro experiments, the fracture strength of a femur with a lesion that penetrates either the inferior-medial or superior-lateral cortex of the neck is approximately 45% less than the fracture strength of the paired intact femur; based on the second series, the fracture strength with the inferior-medial lesion is approximately 20% less than the fracture strength with the superior-lateral lesion. A series of three-dimensional finite element models were used to predict the fracture strength for anterior and posterior lesions, as well as the inferior-medial and posterior-lateral lesions tested in vitro. Based on a direct comparison of the strengths predicted by the finite element models to the measured in vitro fracture strengths, the finite element models performed poorly. In particular, the application of an anisotropic strength criterion to the stresses predicted by the models resulted in a considerable underestimation of the percentage reduction in the in vitro fracture strength. This may reflect a fundamental inability of a linear, macroscopic continuum-based analysis to predict accurately the fracture strength of a bone structure as complex as the proximal femur. However, despite this lack of agreement in absolute fracture strength, the general trends for gait and stair ascent loading for the inferior-medial and superior-lateral lesions were consistent with the in vitro data. The greatest reduction in strength was predicted for the inferior-medial lesion, followed by the anterior lesion and then the superior-lateral lesion, and the least reduction in strength was predicted for the posterior lesion. Most importantly, the predicted strength ratio varied considerably as a function of the applied loads. Any metastatic lesions of the femoral neck may be especially sensitive to some particular activity, making it difficult to determine precisely the risk of fracture.

Aged↗

PubMed1996

Specificity of training velocity and training load on gains in isokinetic knee joint strength.

The present study investigated the effects of three different strength training regimes on the isokinetic strength profile of the knee extensors (quadriceps, Q) and flexors (hamstrings, H) and if increases in isokinetic strength were accompanied by an enhanced performance during a more complex leg movement, the soccer kick. Twenty-two elite soccer players performed 12 weeks of strength training (three times per week) at either high resistance (HR group: 4 sets, 8 reps, 8RM loading), low resistance (LR group: 4 sets, 24 reps, 24RM loading), loaded kicking movements (LK group: 4 sets, 16 reps, 16RM loading) while one group served as controls (CO group). Isokinetic concentric and eccentric moment of force was obtained (KinCom) as peak moment (Mpeak) and moment at 50 degrees knee flexion (M50) at angular velocities of 30, 120, 240 degrees s-1. Isokinetic knee joint strength was unchanged in groups LR, LK, CO. However, after the HR strength training, concentric Mpeak (+/- SD) increased (P < 0.01) at 30 degrees s-1 (Q, 258 +/- 37 to 297 +/- 57 Nm; H, 122 +/- 22 to 140 +/- 21 Nm). Furthermore, eccentric Mpeak increased at 30, 120 and 240 degrees s-1 (Q, 274 +/- 60 to 345 +/- 57 Nm (P < 0.01), 291 +/- 56 to 309 +/- 49 Nm and 275 +/- 43 to 293 +/- 36 Nm (P < 0.05), respectively; H, 143 +/- 32 to 158 +/- 25 Nm, 152 +/- 39 to 169 +/- 31 Nm and 148 +/- 27 to 163 +/- 19 Nm (P < 0.05)). Corresponding increases (P < 0.05) were observed for M50. The H/Q ratio calculated as eccentric hamstring strength divided by concentric quadriceps strength (Hecc/Qcon, representative for knee extension) at 240 degrees s-1 increased (P < 0.05) from 107 to 118% (based on Mpeak) and from 90 to 105% (M50). Kicking performance estimated by maximal ball flight velocity was unaffected by any of the strength training regimes investigated. In conclusion, only heavy-resistance strength training induced increases in isokinetic muscle strength in the absence of learning effects. Concentric strength gains were observed at the actual velocity of training, while eccentric strength gains were found over the entire range of velocities examined. The capacity of the hamstring muscles for providing stability to the knee joint during fast extension was augmented as a result of the heavy-resistance strength training. Strength training should be integrated with other types of training involving the actual movement pattern in order to increase the performance within more complex movement patterns.

Adult↗

PubMed1991

Effects of low ionic strength media on passive human red cell monovalent cation transport.

1. The effect of low ionic strength media on the residual, i.e. (ouabain + bumetanide + Ca2+)-insensitive, K+ influx was characterized in human red blood cells. 2. This K+ flux was enhanced significantly in isotonic solutions of low ionic strength using sucrose to maintain constant osmolarity. This effect was found for fresh red blood cells as well as for stored (bank) red blood cells. However, the absolute magnitude of K+ influx in solutions of low ionic strength was halved for stored red blood cells. 3. Anion replacement of Cl- by CH3SO4- did not affect residual K+ fluxes, showing that Cl- -dependent transport pathways (e.g. the KCl co-transporter) are not involved in the low ionic strength effect. 4. The enhanced K+ influx in low ionic strength media was reversible when the cells were resuspended in a solution of physiological ionic strength. 5. K+ influx measured in light and dense fractions of erythrocytes (separated by centrifugation and corresponding to samples enriched with either 'young' or 'mature' red cells) showed that the low ionic strength effect does not change markedly with cell age. 6. Low ionic strength media elevated residual, i.e. (ouabain + bumetanide + Ca2+)-insensitive, influx of both K+ and Na+ by about the same amount. In both cases the flux was linear with concentration in the range investigated (0.25-10 mM). No significant increase in the uptake of the cations Ca2+ and lysine in low ionic strength solutions could be found. 7. In CH3SO4- -containing solutions of physiological ionic strength the residual K+ influx was almost independent of cell volume, whereas this flux in CH3SO4- -containing solutions of low ionic strength declined as cell volume was increased. 8. K+ flux measurements in solutions of different external pH, where NaCl was replaced by sodium gluconate or sodium glucuronate, showed that the reduced ionic strength is of more importance for the enhanced residual K+ influx than the changed transmembrane potential or the changed intracellular pH. However, a small pH dependence could be found, the K+ flux passing through a minimum around pHi 7.3. 9. Hydrostatic pressure enhanced the residual K+ flux in media of low ionic strength synergistically, so that very large fluxes (greater than 10 mmol (1 cells)-1 h-1) were obtained at 40 MPa. The apparent activation volumes (delta V*) for the pressure-sensitive K+ flux were -108 and -69 ml mol-1 in low ionic strength or physiological ionic strength solutions respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Biological Transport↗

PubMed1996

Bone mass, areal, and volumetric bone density are equally accurate, sensitive, and specific surrogates of the breaking strength of the vertebral body: an in vitro study.

The validity of the bone mineral density (BMD) measurement depends on its accuracy as a predictor of the breaking strength of bone. As the breaking strength is proportional to the square of the apparent density, a small error in the calculation of BMD may result in a larger error in the predicted bone strength. The aims of this study were (i) to determine whether inaccuracies in the measurement of the dimensions, projected area, and volume of the vertebral body (used to derive the areal and volumetric BMD) result in errors in the predicted breaking strength and (ii) to compare the accuracy, sensitivity, and specificity of bone mineral content (BMC), areal BMD, volumetric BMD, and volumetric bone mineral apparent density (BMAD) as surrogates of bone strength. We measured the BMC (by densitometry), dimensions and volume (using calipers, densitometry, the Carter et al. and Peel and Eastell methods), and breaking strength (using the Instron 1114 apparatus, Newtons, N) of 22 vertebral body specimens. All methods resulted in errors in height, width, and depth between -11.3 +/- 1.0 and 30.4 +/- 1.8% relative to the "gold" standard caliper method. The vertebral body volume (of 38.0 +/- 1.2 cm3) measured by submersion was used as the gold standard to derive the volumetric BMD gold standard (of 0.162 +/- 0.01 g/cm3). All methods, except the Peel and Eastell method, resulted in errors ranging between -10.7 +/- 1.5 and 56.9 +/- 3.4% in vertebral body volume and -35.6 +/- 1.5 to 12.6 +/- 1.8% in volumetric BMD (all p < 0.0005). The same absolute value for volumetric BMD predicted a breaking strength that differed according to the method used to derive BMD. For example, a volumetric BMD of 0.162 g/cm3 predicted a breaking strength of 6208 N (submersion method), 5473 N (caliper method), 6095 N (Peel and Eastell method), 7697 N (DXA method), and 9470 N (Carter et al. method). The mean volumetric BMD derived by each method differed (0.181, 0.165, 0.133, and 0.104 g/cm3, respectively). However, all were accurate; each predicted a similar breaking strength (6177, 6217, 6209, and 6221 N respectively). Likewise, breaking strengths predicted by the mean BMC, areal BMD by calipers, and areal BMD by dual-energy X-ray absorptiometry (DXA) were 6267, 6214, and 6244 N, respectively. The methods were equally sensitive; a 1 standard deviation (SD) decrease in volumetric BMD resulted in a similar decrease in the breaking strength of 1818 (caliper), 2080 (Peel and Eastell), 2001 (DXA), and 1625 N (BMAD by Carter et al). A 1 SD decrease in BMC, areal BMD (using calipers) and areal BMD (using DXA) predicted a decrease in the breaking strength of 2019, 1738, and 1825 N, respectively. All methods were equally specific; the variance in bone strength explained by bone mass did not differ for volumetric BMD (38-61% depending on the method), BMC (58%), or areal BMD (48%). In conclusion, despite errors in the measurement of the dimensions of the vertebral body, bone mass, areal, and volumetric bone density are equally accurate, sensitive, and specific surrogates of the breaking strength of bone in vitro.

Absorptiometry, Photon↗

PubMed2002

Comparison of 1 and 2 days per week of strength training in children.

The purpose of this study was to compare the effects of 1 and 2 days per week of strength training on upper body strength, lower body strength, and motor performance ability in children. Twenty-one girls and 34 boys between the ages of 7.1 and 12.3 years volunteered to participate in this study. Participants strength trained either once per week (n = 22) or twice per week (n = 20) for 8 weeks at a community-based youth fitness center. Each training session consisted of a single set of 10-15 repetitions on 12 exercises using child-size weight machines. Thirteen children who did not strength train served as age-matched controls. One repetition maximum (1RM) strength on the chest press and leg press, handgrip strength, long jump, vertical jump, and flexibility were assessed at baseline and posttraining. Only participants who strength trained twice per week made significantly greater gains in 1RM chest press strength, compared to the control group (11.5 and 4.4% respectively, p < .05). Participants who trained once and twice per week made gains in 1RM leg press strength (14.2 and 24.7%, respectively) that were significantly greater than control group gains (2.4%). On average, participants who strength trained once per week achieved 67% of the 1RM strength gains. No significant differences between groups were observed on other outcome measures. These findings support the concept that muscular strength can be improved during the childhood years and favor a training frequency of twice per week for children participating in an introductory strength training program.

Adaptation, Physiological↗

PubMed2006

Strength, but not muscle mass, is associated with mortality in the health, aging and body composition study cohort.

BACKGROUND: Although muscle strength and mass are highly correlated, the relationship between direct measures of low muscle mass (sarcopenia) and strength in association with mortality has not been examined. METHODS: Total mortality rates were examined in the Health, Aging and Body Composition (Health ABC) Study in 2292 participants (aged 70-79 years, 51.6% women, and 38.8% black). Knee extension strength was measured with isokinetic dynamometry, grip strength with isometric dynamometry. Thigh muscle area was measured by computed tomography (CT) scan, and leg and arm lean soft tissue mass were determined by dual energy x-ray absorptiometry (DXA). Both strength and muscle size were assessed as in gender-specific Cox proportional hazards models, with age, race, comorbidities, smoking status, level of physical activity, fat area by CT or fat mass by DXA, height, and markers of inflammation, including interleukin-6, C-reactive protein, and tumor necrosis factor-alpha considered as potential confounders. RESULTS: There were 286 deaths over an average of 4.9 (standard deviation = 0.9) years of follow-up. Both quadriceps and grip strength were strongly related to mortality. For quadriceps strength (per standard deviation of 38 Nm), the crude hazard ratio for men was 1.51 (95% confidence interval, 1.28-1.79) and 1.65 (95% confidence interval, 1.19-2.30) for women. Muscle size, determined by either CT area or DXA regional lean mass, was not strongly related to mortality. In the models of quadriceps strength and mortality, adjustment for muscle area or regional lean mass only slightly attenuated the associations. Further adjustment for other factors also had minimal effect on the association of quadriceps strength with mortality. Associations of grip strength with mortality were similar. CONCLUSION: Low muscle mass did not explain the strong association of strength with mortality, demonstrating that muscle strength as a marker of muscle quality is more important than quantity in estimating mortality risk. Grip strength provided risk estimates similar to those of quadriceps strength.

Age Factors↗

PubMed2006

The loss of skeletal muscle strength, mass, and quality in older adults: the health, aging and body composition study.

BACKGROUND: The loss of muscle mass is considered to be a major determinant of strength loss in aging. However, large-scale longitudinal studies examining the association between the loss of mass and strength in older adults are lacking. METHODS: Three-year changes in muscle mass and strength were determined in 1880 older adults in the Health, Aging and Body Composition Study. Knee extensor strength was measured by isokinetic dynamometry. Whole body and appendicular lean and fat mass were assessed by dual-energy x-ray absorptiometry and computed tomography. RESULTS: Both men and women lost strength, with men losing almost twice as much strength as women. Blacks lost about 28% more strength than did whites. Annualized rates of leg strength decline (3.4% in white men, 4.1% in black men, 2.6% in white women, and 3.0% in black women) were about three times greater than the rates of loss of leg lean mass ( approximately 1% per year). The loss of lean mass, as well as higher baseline strength, lower baseline leg lean mass, and older age, was independently associated with strength decline in both men and women. However, gain of lean mass was not accompanied by strength maintenance or gain (ss coefficients; men, -0.48 +/- 4.61, p =.92, women, -1.68 +/- 3.57, p =.64). CONCLUSIONS: Although the loss of muscle mass is associated with the decline in strength in older adults, this strength decline is much more rapid than the concomitant loss of muscle mass, suggesting a decline in muscle quality. Moreover, maintaining or gaining muscle mass does not prevent aging-associated declines in muscle strength.

Aged↗

PubMed2001

Acute muscle damage as a stimulus for training-induced gains in strength.

PURPOSE: The purpose of this study was to investigate the effect of a single acute bout of maximal eccentric work upon the strength gains during 9 subsequent weeks of strength training. Eccentric work causes acute muscle damage that may initiate compensatory hypertrophy and enhance training-induced gains in strength. METHODS: Twenty-six healthy adults (21 +/- 1 yr, 7 women) trained the elbow flexors 3 d per week for 9 wk. One arm (C) performed purely conventional isotonic training, i.e., lifting and lowering. The other arm (E) began with a single bout of maximal eccentric work but thereafter undertook identical isotonic training. Every week dynamic lifting strength (1 RM) and isometric strength were measured. RESULTS: The results indicated that an acute bout of eccentric muscle damage does not accentuate training-induced gains in strength. Isometric strength of arm E fell by 15 +/- 2% (mean +/- SEM) 2 d after the bout of eccentric work, and, 4 d afterward, plasma creatine kinase levels were 1502 +/- 397 IU.L-1. Although arm E displayed rapid gains in strength from 2 d after the bout of eccentric work, these were not sustained, and for several weeks arm E showed significantly smaller gains in strength than arm C (isometric strength, 2 wk; dynamic lifting strength, 5 wk). CONCLUSIONS: After 9 wk of training, the gains in both isometric and dynamic lifting strength were similar for the two arms. A single bout of damaging eccentric work did not enhance the response to conventional strength training and significantly compromised strength gains for several weeks.

Adaptation, Physiological↗

PubMed1997

Physical activity and the changes in maximal isometric strength in men and women from the age of 75 to 80 years.

OBJECTIVE: To research the natural changes in maximal isometric strength, over a period of 5 years, in men and women aged 75 at baseline, and to study the effect of everyday physical activity on strength alterations. DESIGN: A 5-year longitudinal study. SETTING: Exercise laboratory. PARTICIPANTS: The target group in 1989 was the total 75-year-old population of Jyväskylä. One hundred one men (81%) and 186 women (75%) participated in baseline strength tests, and after 5 years, 55 men and 111 women (70% and 72% of the survivors) took part in the follow-up measurements. METHODS: Maximal isometric hand grip, arm flexion, knee extension, trunk flexion, and trunk extension forces were measured using dynamometers. Self-rated physical activity was recorded using a scale by Grimby (1986). Strength changes were compared between groups based on the amount of everyday physical activity: (1) remained active (AA, 24 men, 24 women); (2) remained sedentary (SS, 11 men, 43 women); (3) decreased activity (AS, 11 women); and (4) increased activity (SA, 32 women). AS and SA could be formed for women only because of the small number of men. All analyses were stratified by gender. MAIN RESULTS: The average percentage change in strength over 5 years among survivors varied from a 4% increase in knee extension strength observed in men and women to a 16% decrease in grip strength in women. The grip strength decrease was greater in women than men. The AA men maintained their trunk extension strength at a higher level than the SS men. Time by group interactions in men were not significant. In women, the rate of decline in AS was 32% in grip and 27% in elbow flexion strength, which was greater than in the other activity groups. The AA women retained their knee extension strength at a higher level than the other groups. Those who died before follow-up tests exhibited poorer strength test results at baseline. Physical activity decreased over follow-up. CONCLUSIONS: Strength alterations with age differed between muscle groups. Undertaking everyday physical activities such as household work, walking, and gardening, which are also the most common physically demanding activities of older people, may play an important role in maintaining strength at an adequate level for independent living.

Aged↗

PubMed2005

Serum albumin and muscle strength: a longitudinal study in older men and women.

OBJECTIVES: To examine whether low serum albumin is associated with low muscle strength and future decline in muscle strength in community-dwelling older men and women. DESIGN: Population-based cohort study. SETTING: The Longitudinal Aging Study Amsterdam. PARTICIPANTS: Six hundred seventy-six women and 644 men aged 65 to 88. MEASUREMENTS: Serum albumin was determined at baseline. Muscle strength was assessed using grip strength at baseline, after 3 (n=1,009), and 6 (n=741) years. The outcomes were continuous baseline muscle strength, 3- and 6-year change in muscle strength, and a dichotomous indicator for substantial decline (a decrease if > or =1 standard deviations for women=11 kg, for men=12 kg) in muscle strength. RESULTS: Mean serum albumin concentration+/-standard deviation was 45.0+/-3.3 g/L for women and 45.2+/-3.2 g/L for men. At baseline, adjusting for age, lifestyle factors, and chronic conditions, lower serum albumin was cross-sectionally associated with weaker muscle strength (P<.001) in women and men. After 3 years of follow-up, mean decline in muscle strength was -5.6+/-10.9 kg in women and -9.6+/-11.9 kg in men. After adjustment for potential confounders, lower serum albumin was associated with muscle strength decline over 3 years (P<.01) in women and men (beta=0.57, standard error (SE)=0.18; beta=0.37, SE=0.16, respectively). Lower serum albumin was also associated with substantial decline in muscle strength in women (per unit albumin (g/L) adjusted odds ratio (OR)=1.14, one-sided 95% confidence limit (CL)=1.07) and men (per unit albumin (g/L) adjusted OR=1.14, 95% CL=1.08). Similar but slightly weaker associations were found between serum albumin and 6-year change in muscle strength (P<.05). CONCLUSION: These results suggest that low serum albumin, even within the normal range, is independently associated with weaker muscle strength and future decline in muscle strength in older women and men.

Aged↗

PubMed1998

Grip strength changes over 27 yr in Japanese-American men.

The aim of this study was to describe changes in grip strength over a follow-up period of approximately 27 yr and to study the associations of rate of strength decline with weight change and chronic conditions. The data are from the Honolulu Heart Program, a prospective population-based study established in 1965. Participants at exam 1 were 8,006 men (ages 45-68 yr) who were of Japanese ancestry and living in Hawaii. At follow-up, 3,741 men (age range, 71-96 yr) participated. Those who died before the follow-up showed significantly lower grip-strength values at baseline than did the survivors. The average annualized strength change among the survivors was -1.0%. Steeper decline (>1.5%/yr) was associated with older age at baseline, greater weight decrease, and chronic conditions such as stroke, diabetes, arthritis, coronary heart disease, and chronic obstructive pulmonary disease. The risk factors for having very low hand-grip strength at follow-up, here termed grip-strength disability (</=21 kg, the lowest 10th percentile), were largely same as those for steep strength decline. However, the age-adjusted correlation between baseline and follow-up strength was strong (r = 0.557, P < 0.001); i.e., those who showed greater grip strength at baseline were also likely to do so 27 yr later. Consequently, those in the lowest grip-strength tertile at baseline had about eight times greater risk of grip-strength disability than those in the highest tertile because of their lower reserve of strength. In old age, maintenance of optimal body mass may help prevent steep strength decrease and poor absolute strength.

Aged↗

PubMed1994

[Changes in abdominal muscle strength with respect to aging].

It has been generally agreed that muscle strength decreases with advance of age in adulthood. In order to study the effect of aging in abdominal muscle strength, abdominal muscle strength, height, body weight and grip strength were measured in 144 healthy subjects aged from 20 to 88 years old. The abdominal muscle strength was measured using a grip dynamometer. Curve between aging and strength revealed that the abdominal muscle strength gradually decreased with aging during many decades, but rapidly decreased in the fifth decade and over in males and seventh decade and over in females. Among these data, significant correlations were observed between abdominal muscle strength and age (only in males; r = -0.64), abdominal muscle strength and grip strength (in males; r = 0.75, in females; r = 0.47), age and grip strength (in males; -0.72, in females; r = -0.60), and, age and height (in males; r = -0.55, in females; r = -0.46). The results suggest that decrease of abdominal muscle strength is due to aging, although the degree of the decrease is affected by the generation studied. The method to measure abdominal muscle strength originally developed by us is easy and useful to understand changes of age-related muscular strength.

Abdominal Muscles↗

PubMed2001

Grip strength measurement in competitive ten-pin bowlers.

BACKGROUND: In an attempt to find a more specific grip strength test for bowlers, the conventional grip strength test was modified such that only the fingers used in holding the ball are tested. The objective of this study was to assess the test-retest reliability of this modified bowling grip strength test, to assess the agreement between the bowling and the conventional grip strength tests, and to examine the correlation between the modified test and bowling performance in competitive bowlers. METHODS. EXPERIMENTAL DESIGN: This research was conducted in two parts, each with a different study sample. Study I was a cross-sectional study to assess the correlation between the bowling grip strength and the bowling score. Study II was a comparative study to obtain the test-retest reliability for both the bowling and conventional grip strength tests, and to assess the agreement between the two tests. SETTING AND SUBJECTS: for study I, the subjects were 39 members (26 males and 13 females) of the Singapore National Ten-Pin Bowling Training Squad. Bowling grip strength was measured within one month prior to the selection trials for the national squad, the results of which were used as a measure of bowling performance. For study II, the subjects were 21 members (12 males and 9 females) of the Singapore National Ten-Pin Bowling Squad that was formed after the selection trials. INTERVENTIONS: none. MEASURES: Bowling grip strength, conventional grip strength, and bowling score. RESULTS: The test-retest reliability of the bowling grip strength measurement (r = 0.91, p < 0.01) was comparable to that of the conventional five-finger grip (r = 0.93, p < 0.01). The single measure intraclass correlation coefficient between the bowling and conventional grip strength tests was 0.77; the 95% confidence interval was 0.51 and 0.90. However, the correlation coefficient between the bowling grip strength test and bowling score (r = 0.27) was not significant. CONCLUSIONS: The bowling grip strength test has a high test-retest reliability, and a moderate agreement with the conventional grip strength test. However, despite using only the bowling fingers, the test was unable to predict bowling performance in elite bowlers.

Adolescent↗