This study investigated the effects of 12 weeks of exercise training on functional fitness, assessed by Senior Fitness Tests, and health-related quality of life (HRQL), assessed by the Medical Outcomes Study Short Form-36 (MOS SF-36), in previously inactive senior center adults (n = 10 males and n = 28 females). Exercise training resulted in significant improvements for chair stand, arm curl, two-minute step, and sit-and-reach tests (all p < 0.001). Role physical (p < 0.001), bodily pain (p = 0.001), and vitality (p = 0.002) MOS SF-36 domains also improved. The results suggest that participation in exercise by senior center members can provide important additional benefits.

The CA-repeat polymorphism in the insulin-like growth factor 1 (IGF1) gene promoter region has been associated with strength and circulating IGF-I protein levels. The purpose of the study was to determine if the IGF1 CA-repeat polymorphism influences muscle power at baseline and in response to ST in older adults. Knee extensor peak power (PP) was measured at 50, 60, and 70% of 1-RM strength before and after 10 weeks of unilateral knee extensor ST in older adults, aged 50–85 years, to determine the changes in absolute and relative PP with ST. Subjects (N = 114) were genotyped for the IGF1 CA-repeat polymorphism and grouped as homozygous for the 192 allele, heterozygous, or non-carriers of the 192 allele. The 192 homozygotes had significantly lower baseline PP at 50, 60, and 70% of 1-RM strength than the non-carriers when age, sex, and baseline fat-free mass were covaried (all P < 0.05). This same relationship was observed when the highest PP within these ranges was compared (e.g., 317.6 ± 13.5 for 192 homozygotes and 380.2 ± 16.3 for non-carriers of the 192 allele, P < 0.05). Both absolute and relative PP increased significantly with ST in all genotype groups as expected, but there were no significant relationships among IGF1 genotypes and any of the PP changes. Despite a significant relationship between IGF1 genotype and knee extensor peak power at baseline, IGF1 genotype does not appear to influence changes in knee extensor peak power with ST.

Autism spectrum disorders (ASDs) can influence neuromuscular function including walking gait. This effect on neuromuscular function can impact quality of life in individuals with ASDs. Exercise training has been shown to be effective in improving walking gait in other populations. PURPOSE: To determine the effect of 8 weeks of exercise training on gait function during a fast walk in young adults with ASDs. METHODS: Changes in gait function including velocity, cadence, stride length, base of support, and percentage of time spent in double support during a fast walk were assessed before and after 8 weeks of exercise training in the Towson University Wellness F.I.T Program. In addition, changes in the coefficient of variation for these parameters of gait function were compared to determine if training improved step-to-step variability during a fast walk. The Wellness F.I.T. Program consisted of 2 days per week of exercises for cardiorespiratory fitness, muscular strength, muscular endurance, flexibility, and balance. Participants were male (n=11) adults (19-24 yrs) from the community diagnosed with ASDs. Changes in gait function were assessed using a GaitRite walking system. Paired t-tests were used to test for significant changes in body weight, body mass index (BMI), parameters of gait function and coefficients of variation for these parameters before and after participation in the Wellness F.I.T. Program. RESULTS: There were no significant changes in body weight or BMI with exercise training. However, there was a significant improvement in cadence (127.6 ± 5.4 vs. 122.1 ± 5.0 steps/min, P = 0.037). Accompanying this improvement in cadence was an increase in the coefficient of variation (3.68 ± 0.44 vs. 1.69 ± 0.33, P = 0.01). There was a trend for improvement in time spent during the gait cycle in double support with exercise training (4.9 ± 0.7 vs. 7.0 ± 1.1%, P = 0.054). There were no significant changes in the other parameters of gait function before and after 8 weeks of training. CONCLUSIONS: These preliminary results suggest that in young adults with ASDs that exercise training at least 2 days per week for 8 weeks may improve gait function during a fast walk.

The mission of the Baltimore County Department of Aging (BCDA) is to develop and administer programs and activities that support senior citizens in their efforts to remain healthy, active, and independent members of the community and to provide, coordinate, and advocate for services which ensure the highest quality of life for both active and health-impaired seniors, their families, and caregivers. PURPOSE: To survey functional ability in older adults attending the Senior Expo 2009 event sponsored by the BCDA. METHODS: 307 men and women aged 69.8±7.9 yrs (range 52-92) volunteered to perform functional tests typically assessed in this population (chairs stand, arm curl, back scratch, 8ft up-and-go) as well as percent body fat (%BF) via BIA, Height (ht), Weight (wt) and BMI. Data were analyzed for mean±SD and t-tests for differences between genders. RESULTS: Of the 307 at the event, there were significantly more women in attendance (28%M vs 72%W). Chair stand was 14.6±4.3stands in 30 sec, with more stands completed by men. Arm curl was 18.2±5.6reps in 30 sec, with more reps completed by men. Back scratch was -3.5±4.8 in, with men demonstrating more flexibility. 8ft up-and-go was 5.9±1.6sec with no difference in genders. %BF was 33.9±9.2% with women having higher %BF. Ht was 64.9±3.6in, Wt was 75.1±15.7kg, as men were taller and heavier. There was no difference in BMI (27.5±5.1kg/m2). BCDA has 19 senior centers of which 8 contain fitness centers each with Directors. During 7/2008-6/2009, there were 48,400 visits from the 964 members enrolled across 8 fitness centers out of a total of 15,931 total members at the 19 centers. CONCLUSIONS: These senior centers in Baltimore County serve as community focal points for programs, activities and services for residents age 60 and older. Most centers are nationally accredited by National Institute of Senior Centers. The Senior Expo outreach event was successful surveying over 300 older adults in the community in terms of functional ability. Generally, men had more functional ability than women in these tests, even though there were significantly more women in attendance. One future goal of these outreach events is to increase awareness of functional ability and increase the enrollment of older adults at the senior fitness centers.

Autism spectrum disorders cause a primary impairment in social interaction, but also affect neuromuscular function. This can impact participation in physical activity and affect quality of life. Exercise has been shown to have an impact on neuromuscular function in various populations. PURPOSE: To determine the effect of exercise on neuromuscular function as assessed by balance and gait, in young adults on the autism spectrum who attend the Towson University Center for Adults with Autism Spectrum Disorders Wellness Program. METHODS: Balance and gait were assessed before and after 6 weeks of participation in aerobic and strength and conditioning exercises. The program consisted of 2 days per week of exercises for cardiorespiratory fitness, muscular strength, muscular endurance, flexibility, and balance for 1.5 hours, including a group warm-up and cooldown that promoted social interaction and provided healthy lifestyle education. Participants were male (n=7) and female (n=1) adults (20-34 yrs) from the community who are on the autism spectrum. Changes in balance and gait were assessed using the Tinetti Performance Oriented Mobility Assessment (POMA). Paired t-tests were used to test for significant differences in changes in balance, in gait at normal pace, and in gait at a rapid pace before and after 6 weeks of participation in the Towson University Autism Wellness Program. RESULTS: There was a significantly greater increase in normal gait scores after participation in the program compared with before (10.25±1.38 vs. 8.38±2.50, P=0.008). Also, there was a significantly greater increase in rapid pace gait scores after participation in the Towson University Autism Wellness Program compared with before (10.38±1.69 vs. 8.00±2.10, P=0.001). There was no significant difference in balance scores before and after 6 weeks of participation. CONCLUSIONS: These preliminary results suggest that in young adults on the autism spectrum that exercise at least 2 days per week for 6 weeks may improve neuromuscular function as assessed by normal and rapid pace gait.

Successful aging encompasses physical, functional, social, and psychological health, which are all important aspects in maintaining quality of life. PURPOSE: To determine the effect of exercise on health-related quality of life (HRQL) and functional ability, as assessed by ability to carry out activities of daily living (ADL), in older adults who attend senior centers. METHODS: Changes in HRQL and ability to carry out ADLs were assessed after 12 weeks of endurance training (ET), following ACSM guidelines, in 16 previously inactive older (72±6 yrs) men (n=3) and women (n=13) and compared with changes in HRQL and ability to carry out ADLs in 16 aged-matched (76±7 yrs) inactive controls (men (n=1), women (n=15)). All research participants were members of the Baltimore County Department of Aging Senior Centers. Changes in HRQL for several domains including: physical functioning, physical health-related role limitations, bodily pain, general health, vitality, social functioning, mental health-related role limitations, and mental health were assessed by the Medical Outcomes Survey Short Form-36 (MOS SF-36) questionnaire. Changes in ability to carry out ADLs were assessed using the Senior Fitness Tests (SFT), which included: chair stand, arm curl, 2-minute step, chair sit-and-reach, back scratch, and 8-foot up-and-go tests. ANCOVA was used to test for significant differences in changes in HRQL and ability to carry out ADLs between the ET and control groups. RESULTS: There was a significantly greater increase in the physical health-related role limitations domain in the ET group compared with controls (12±19 vs. -8±20, P=0.01). Also, there was a significantly greater increase in the number of steps completed in the 2-minute step test in the ET group compared with controls (15±10 vs. 4±8, P=0.01). There were no other significant differences between the ET and control groups for changes in the other HRQL domains or the other SFTs. CONCLUSIONS: These preliminary results suggest that in older adults who attend senior centers, ET may improve aerobic fitness and the ability to carry out work and other physical daily activities. Supported by Towson University Faculty Development and Research Committee Grant

To examine the influence of insulin-like growth factor (IGF) pathway gene polymorphisms on muscle mass and strength responses to strength training (ST), we studied 128 White and Black men and women before and after a 10-wk single-leg knee extension ST program. One-repetition maximum strength, muscle volume (MV) via computed tomography, and muscle quality (MQ) were assessed at baseline and after 10 wk of ST. There was a significant combined IGF1 cytosine adenine (CA) repeat gene effect, which included both the IGF1 CA repeat main effect and IGF1 CA repeat x PPP3R1 insertion-deletion (I/D) gene x gene interaction effect, on the changes in strength (P < 0.01) and MQ (P < 0.05) with ST. There was a trend for a significant gene x gene interaction between IGF1 CA repeat and PPP3R1 I/D for changes in strength (P = 0.07) and MQ (P = 0.06) with ST. The influence of the PPP3R1 A-202C gene polymorphism on change in MV with ST approached significance (P = 0.06). The IGF1 CA repeat polymorphism had a significant influence on the change in strength and MV combined with ST (P < 0.05), whereas the influence of the PPP3R1 I/D polymorphism approached significance (P = 0.08). There were no associations between the IGFBP3 A-202C gene polymorphism and the muscle phenotypic responses to ST. These data suggest that two of the three IGF pathway gene polymorphisms identified in this study influence muscle phenotypic responses to ST in both black and white older men and women.

BACKGROUND The alpha-actinin-3 (ACTN3) R577X polymorphism has been associated with muscle power performance in cross-sectional studies. METHODS We examined baseline knee extensor concentric peak power (PP) and PP change with approximately 10 weeks of unilateral knee extensor strength training (ST) using air-powered resistance machines in 71 older men (65 [standard deviation = 8] years) and 86 older women (64 [standard deviation = 9] years). RESULTS At baseline in women, the XX genotype group had an absolute (same resistance) PP that was higher than the RR (p =.005) and RX genotype groups (p =.02). The women XX group also had a relative (70% of one-repetition maximum [1-RM]) PP that was higher than that in the RR (p =.002) and RX groups (p =.008). No differences in baseline absolute or relative PP were observed between ACTN3 genotype groups in men. In men, absolute PP change with ST in the RR (n = 16) group approached a significantly higher value than in the XX group (n = 9; p =.07). In women, relative PP change with ST in the RR group (n = 16) was higher than in the XX group (n = 17; p =.02). CONCLUSIONS The results indicate that the ACTN3 R577X polymorphism influences the response of quadriceps muscle power to ST in older adults.

BACKGROUNDThere is little information regarding the effects of strength training on intermuscular fat (IMF). This study examines changes in IMF in response to strength training in carriers of the adrenergic receptor (ADR) beta2Glu27 polymorphism versus noncarriers and between carriers of ADRalpha2b Glu(9) polymorphism versus noncarriers.METHODSMidthigh IMF and muscle area were measured by computed tomography (CT) before and after 10 weeks of single-leg strength training in healthy, sedentary middle-aged and older (50-83 years) men (n = 46) and women (n = 52) in both their trained and untrained (control) legs.RESULTSThe strength training program resulted in a substantial increase in one-repetition maximum strength (p <.001) and muscle area (p <.001), but no significant changes in IMF in the whole group. However, IMF was significantly reduced with strength training in participants carrying ADRbeta2 Glu27 (-2. 3 +/- 1.0 cm(2), p =.028), but no significant change was observed with ADRbeta2 Glu27 noncarriers. The decrease in IMF in ADRalpha2b Glu(9) carriers (-1.9 +/- 1.0 cm(2), p =.066) was significantly different (-2.9 +/- 1.5 cm(2), p =.043) from a nonsignificant increase in ADRalpha2b Glu(9) noncarriers. ADRbeta2 Glu27 carriers who also carried ADRalpha2b Glu(9) significantly lost IMF with strength training (-3.8 +/- 1.5 cm(2), p =.018).CONCLUSIONADR genotype influences IMF response to strength training.

Peripheral vasculature resistance can play an important role in affecting blood pressure and the development of cardiovascular disease. A better understanding of the genes that encode vasodilators, such as adenosine, will provide insight into the mechanisms underlying cardiovascular disease. We tested whether the adenosine monophosphate deaminase-1 (AMPD1) C34T gene polymorphism was associated with the vasodilatory response to ischemia in Caucasian females aged 18-35 years. Blood samples (n = 58) were analyzed for the C34T variant and resulted in the following genotype groups: CC (n = 45) and CT (n = 13). Mean blood pressure (MBP), heart rate, and forearm blood flow (FBF) measured by venous occlusion plethysmography were measured at baseline and at 1 (peak FBF), 2 and 3 min of vasodilation during reactive hyperemia following 5 min of arm ischemia. To control for interindividual variability in baseline FBF and forearm vascular resistance (FVR) the percent change in FBF and FVR were calculated for each min. The percent decrease in FVR was significantly greater in the CT compared to the CC genotype group (-40+/-4% vs. -24+/-3%, P = 0.01) during the 2nd min of reactive hyperemia. The percent increase in FBF tended to be greater in the CT compared to the CC genotype group (+69+/-9% vs. +42+/-9%, P = 0.07) during the 2nd min of reactive hyperemia after adjustment for percent body fat. Consistent with previous findings of increased production of adenosine during exercise in individuals carrying a T allele, our findings suggest that the AMPD1 C34T polymorphism is associated with vasodilatory response to ischemia in the peripheral vasculature because individuals with the T allele had a greater vasodilatory response to ischemia.

To determine sex and race differences in muscle power per unit of muscle contraction, knee-extensor muscle power normalized for knee-extensor muscle volume was measured in 79 middle-aged and older adults (30 men and 49 women, age range 50-85 years). Results revealed that women displayed a 38% faster peak movement velocity than men and African Americans had a 14% lower peak movement velocity than Whites of a similar age when expressed per unit of involved muscle (p < .001). As expected, men exhibited greater knee-extensor strength and peak power per unit of muscle than women, but women had a faster knee-extension movement velocity per unit of muscle than men at the same relative strength level. Moreover, African Americans had greater knee-extensor muscle volume than Whites but exhibited lower knee-extensor strength and lower movement velocity per unit of muscle when tested at the same relative strength levels.

There is little information regarding the independent effects of strength training (ST) on intermuscular adipose tissue (IMAT) and low density muscle (LDM), both of which have adverse effects on health status in the elderly. In addition, we found large inter-individual variation in IMAT and LDM responses to ST, suggesting that these responses may involve a genetic component. Furthermore, alterations in adipose tissue from exercise interventions may be influenced by ADR β2 Glu27Gln and ADR α2b Glu12/Glu9 gene polymorphisms. PURPOSE: To determine the influence of ADR genotypes on IMAT and LDM responses to ST. METHODS: Mid-thigh IMAT and LDM were measured by computed tomography (CT) before and after 10 weeks of single leg ST in 98 healthy, sedentary middle aged and older (50–83 years) men (n = 46) and women (n = 52). CT scans were analyzed using the MIPAV area assessment program (NIH). ADR genotyping was performed using RFLP. RESULTS: The ST program resulted in a substantial increase in 1-RM strength (P <0.01), a significant decrease in IMAT (−1.98 cm2, P <0.05), but no significant change in LDM. IMAT was significantly reduced in Glu27 carriers with ST (−4.6 cm2, P <0.05), but not in Glu27 noncarriers, which resulted in a significant genotype x training interaction (P <0.05). ST increased LDM in Glu27 carriers (4.1 cm2, P <0.05), but did not change LDM in Glu27 noncarriers. CONCLUSIONS: ST reduces IMAT, but not LDM. However, this response is influenced by ADRβ2 Glu27Gln polymorphism, such that Glu27 carriers reduce IMAT with ST while Glu27 noncarriers do not. Supported by NIH Grants R01 AG-4-2148 and AG-1620501.

OBJECTIVE To determine whether angiotensin-converting enzyme (ACE) and angiotensinogen (ACT) genotypes could predict changes in urinary sodium excretion in response to short-term aerobic exercise training (AEX). DESIGN Longitudinal intervention. SETTING The study was conducted at the University of Maryland at College Park and at Baltimore, and the University of Pittsburgh General Clinical Research Center. PARTICIPANTS 31 (age 53 +/- 2 years) sedentary, hypertensive (146 +/- 2/88 +/- 2 mm Hg) African Americans. INTERVENTION Aerobic exercise training (AEX) consisted of seven or eight consecutive days, 50 minutes per day, at 65% of heart rate reserve. Participants underwent a 24-hour period of ambulatory blood pressure (BP) monitoring and urine collection at baseline and 14-18 hours after the last exercise session. MAIN OUTCOME MEASURES Angiotensiongen (AGT) M235T and ACE I/D genotype and sodium excretion and ambulatory BP. RESULTS Average sodium excretion for the entire group independent of genotype increased after AEX (108 +/- 9 vs 143 +/- 12 mEq/day, P=.003). Sodium excretion significantly increased after exercise training in the ACE II (114 +/- 22 vs 169 +/- 39 mEq/day, P=.04), but not in the ID (100 +/- 8 vs 133 +/- 17 mEq/day, P=.12) or DD (113 +/- 18 vs 138 +/- 11 mEq/day, P=.13) genotype groups. In the II genotype group, the increase in sodium excretion was significantly and inversely correlated with decreases in 24-hour diastolic (r= -.88, P=.02) and mean (r= -.95, P=.004) BP. The ACT TT and MT+MM genotype groups similarly increased their sodium excretion by 34 +/- 16 (P=.05) and 37 +/- 17 (P=.05) mEq/day respectively. CONCLUSIONS These results suggest that African American hypertensives with the ACE II genotype may be more susceptible to sodium balance and BP changes with exercise training compared with those with the ID and DD genotypes.

Title of dissertation: THE INFLUENCE OF INSULIN-LIKE GROWTH FACTOR PATHWAY GENE POLYMORPHISMS ON THE STRENGTH TRAINING RESPONSE OF MUSCLE PHENOTYPES IN OLDER ADULTS Brian Dudley Hand, Doctor of Philosophy, 2006 Dissertation directed by: Professor Ben F. Hurley Department of Kinesiology Strength training (ST) is considered an intervention of choice for the prevention and treatment of the adverse consequences of sarcopenia. Our group previously reported that the CA dinucleotide repeat polymorphism in the promoter region of the insulin-like growth factor 1 (IGF1) gene influenced the muscle strength response to ST in Caucasians. Other studies have shown that the insulin-like growth factor binding protein3 (IGFBP-3) is a modulator of IGF-1 in circulation and is present in skeletal muscle. The -202 polymorphism in the promoter region of the IGFBP3 gene has been shown to influence IGFBP-3 levels. In addition, there have been reports that IGF-1 and calcineurin are linked in a common pathway to induce skeletal muscle cell hypertrophy. A previous study has shown that an insertion/deletion (I/D) polymorphism in the gene encoding the regulatory subunit of calcineurin, calcineurin B, influences cardiac hypertrophy. To examine the influence of these IGF pathway gene polymorphisms on muscle mass and strength responses to ST, we studied 128 Caucasian and African American men and women before and after a 10-wk single-leg knee extension ST program. One repetition maximum strength (1 RM), muscle volume (MV), and muscle quality (MQ) were assessed at baseline and after 10 wk of ST. There was a significant combined gene effect, including both IGF1 main effect and IGF1 by calcineurin B (PPP3R1) gene by gene interaction effect, for change in strength with ST (P < 0.01). There was also a significant combined gene effect for IGF1 on change in MQ (P < 0.05). The gene by gene interaction of IGF1 and PPP3R1 by itself, approached significance for change in strength with ST (P = 0.07) and was right on the border of significance for change in MQ (P = 0.05). Moreover, PPP3R1 II homozygotes approached significance for a greater increase in MV with ST than PPP3R1 D-allele carriers (P = 0.06). There were no significant combined gene effect for PPP3R1 (i.e., PPP3R1 main effect combined with PPP3R1 by IGF1 interaction effect) for change in strength or MQ with ST. Also, there were no significant influences of the IGFBP3 polymorphism on muscle phenotypic responses to ST. These data extend our previous findings for IGF1 by indicating that IGF pathway gene polymorphisms may influence muscle phenotypic responses to ST in Caucasian and African American older men and women. THE INFLUENCE OF INSULIN-LIKE GROWTH FACTOR PATHWAY GENE POLYMORPHISMS ON THE STRENGTH TRAINING RESPONSE OF MUSCLE PHENOTYPES IN OLDER ADULTS By Brian Dudley Hand Dissertation submitted to the Faculty of the Graduate School of the University of Maryland, College Park in partial fulfillment of the requirements for the degree of Doctor of Philosophy 2006 Advisory Committee: Professor Ben F. Hurley, Chair Associate Professor Michael D. Brown Professor Larry W. Douglass Professor James H. Hagberg Assistant Professor Stephen M. Roth

Previous reports on the effects of strength training (ST) on muscle power did not report how the training affected power per unit of the muscle involvement (muscle power quality, MPQ), or peak movement velocity (PV). The expression of peak power normalized for muscle volume allows better understanding of potential mechanisms for training-induced adaptations. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. METHODS Sixty-two relatively healthy, previously sedentary older adults (23 older men, 65 ± 1 yr and 39 older women, 66 ± 1 yr) were studied before and after a 10 wk unilateral knee extension ST program. To quantify quadriceps muscle volume (MV), computed tomography (CT) imaging of the trained and untrained thighs was performed. Determination of peak knee extensor power was performed on a customized pneumatic resistance knee extension machine. Velocity and power data were filtered using a 10 Hz, low-pass Butterworth filter to remove sensor noise and obtain peak estimates. RESULTS As a result of the ST program, peak power increased significantly in both men and women at the same absolute (APP; P < 0.001) and relative loads (RPP; P < 0.05). Men had significantly greater increases in APP and RPP than women with ST when covarying for baseline differences (both P < 0.001). However, when each subject was tested at the same absolute load and when peak power was normalized for the muscle volume of the trained knee extensors (i.e., absolute MPQ), women increased their MPQ (P < 0.05), but men did not. Both men and women increased their absolute PV (P < 0.001), but decreased their relative PV significantly with ST (P < 0.01). CONCLUSIONS These data indicate that a moderate-velocity ST program increases muscle power quality in women, but not in men, suggesting that in contrast to men, women increase peak power with ST through adaptations other than muscular hypertrophy. Supported by NIH Grants R01 AG-4-2148 and AG-1620501 and NIH training grant T32AG00219.

The PPP3R1 gene encodes for a calcium-binding regulatory protein, calcineurin B, which has been shown to play an important role in hypertrophy of myocytes by interacting with insulin-like growth factor-1, GATA-2, and NF-ATc1. PURPOSE To determine whether polymorphisms in the PPP3R1 gene influence the effect of strength training (ST) on muscle size and function. METHODS One-repetition maximum (1-RM) strength and muscle volume (MV) of the knee extensors (KE) were measured in 96 previously sedentary older (66±8 yrs) men (n=37) and women (n=59) before and after a 10 wk unilateral ST program. MV was measured by computed tomography. DNA was extracted from whole blood samples and genotypes for the PPP3R1 gene, at exon 2, were determined resulting in 16 A-allele homozygotes (AA, 7 men, 9 women, 66±9 yrs), 59 heterozygotes (AG, 21 men, 38 women, 65±9 yrs), and 21 Gallele homozygotes (GG, 9 men, 12 women, 66±7 yrs). RESULTS The results from ANCOVA revealed a significant difference in change in MV between AA and GG (90±15 vs 134±19 cm3, P=0.04). The difference in change in MV between AG and GG approached significance (104±7 vs 134±19 cm3, P=0.06). When AA and AG genotype groups were combined and compared with GG the change in MV was still significant (102±7 vs 134±19 cm3, P=0.04). At baseline, there were no significant differences in MV or KE 1-RM strength among PPP3R1 genotype groups. Also there were no differences in changes in KE 1-RM strength with ST among PPP3R1 genotype groups. CONCLUSION These data indicate that PPP3R1 genotype influences MV response to ST in older adults. Supported by NIH Grants RO1 AG4-2148, AG1620501, and AG022791

The effects of a 10-wk unilateral knee extension strength training (ST) program on peak power (PP) and peak movement velocity (PV), at given absolute (force load) and relative (same % of 1 repetition maximum) resistances (loads), were examined in 30 older men [64 yr (7 SD)] and 32 older women [62 yr (6 SD)]. PP increased significantly in both men and women at the same absolute (P < 0.001) and relative loads (P < 0.01) with ST. Men had a significantly greater increase in relative PP than women with ST at 60% (P < 0.01) and 70% (P < 0.001) of 1 repetition maximum when covarying for baseline differences and age. However, when each subject was tested at the same absolute load and when PP was normalized for the muscle volume of the trained knee extensors (i.e., absolute muscle power quality), women increased by 9% (P < 0.05), whereas men did not change. Both men and women increased their absolute PV (P < 0.001) but decreased their relative PV significantly with ST (P < 0.05). However, when baseline values and age were covaried, women had significantly less of a decrease in relative PV quality with ST than men (P < 0.01), although the difference was small. These normalized data suggest that ST-induced increases in PP depend on muscular hypertrophy in men, but not in women, providing further support for the hypothesis developed from our previous report (Ivey FM, Tracy BL, Lemmer JT, NessAiver M, Metter EJ, Fozard JL and Hurley BF. J Gerontol A Biol Sci Med Sci 55: B152-B157, 2000) that improvements in muscle function with ST result from nonmuscle mass adaptations to a greater extent in women than men.