Balance performance on the postural stress test: comparison of young adults, healthy elderly, and fallers

The purpose of this study was to compare the postural responses of three groups of individuals--healthy young adults (n = 42; age, 20-40 years); healthy, community-dwelling, elderly individuals (n = 66; age, 60-102 years), and elderly individuals with a history of frequent falls (n = 10; age, 66-95 years)--using the postural stress test (PST). The PST is a simple, clinically applicable, quantitative measure of an individual's ability to withstand a series of graded destabilizing forces applied at the level of the subject's waist. Elderly fallers tend to score lower on the PST than elderly nonfallers, but age-related differences in postural responses during the PST have not been established. Each subject underwent the PST using a method and scoring procedure described previously. Results of this study confirm previous findings that elderly fallers score significantly lower on the PST than either young adult or nonfalling elderly individuals. This study also showed that there was no difference in balance strategy scores between the young adults and the healthy elderly subjects. Therefore, it appears that poor performance on the PST cannot be attributed to age alone, but may be predictive of pathological processes that predispose an individual to frequent falls.     

Kinetic alterations independent of walking speed in elderly fallers

OBJECTIVES: To determine if joint kinetic gait alterations in fallers persist when they attempt to walk at a faster speed that is more comparable with nonfallers' comfortable walking speed. DESIGN: Retrospective, case-control study. Stereophotogrammetric and force platform data were collected. SETTING: A gait laboratory. PARTICIPANTS: Sixteen elderly subjects who had at least 2 falls in the last 6 months from an unclear cause and 23 elderly subjects with no history of repeated falls. MAIN OUTCOME MEASURES: Differences in all major peak joint kinetic (moment and power) values during the gait cycle between elderly nonfallers walking at comfortable speed and elderly fallers walking at (1) comfortable and (2) fast speed. RESULTS: Statistically significant differences present at both comfortable and fast walking speeds were present in 4 sagittal plane parameters. There was an increase in peak external hip flexion moment in stance, a reduction in peak hip extension moment, a reduction in knee flexion moment in preswing, and a reduction in knee power absorption in preswing. CONCLUSION: The presence and persistence of 4 specific alterations in sagittal plane joint kinetics at both comfortable and fast walking speeds imply specific intrinsic pattern differences and allow for new insights into the mechanics of gait in elderly people who fall. The presence of these alterations also suggests they may serve as potential identifiable markers to detect those who may be at risk for falls.     

Using crutches during walking possibly reduces gait imagery accuracy among healthy young and older adults

[Purpose] Although crutches are widely used in the field of rehabilitation to improve gait performance, patients usually have difficulties using them, and this may increase their risks for falls. This study aimed to define the accuracy of gait imagery during walking with and without crutches, in healthy young and older adults, using the mental chronometry method. [Participants and Methods] Overall, 99 healthy young (mean age, 20.2 ± 1.0 years) and 39 healthy older adults (mean age, 71.3 ± 2.9 years) performed the imagery and execution tasks, which involved walking through a distance of 10 meters both with and without crutches. Using the mental chronometry method, the accuracy of the motor imagery was defined as the difference between the imagery time and the actual execution time. Two-way analysis of variance and one-sample t-tests were performed to evaluate the accuracy of the gait imagery. [Results] Both the young and older adults significantly overestimated their gait speeds when using crutches; the overestimation was larger among the older adults. [Conclusion] The overestimations indicate that participants estimated their gait speeds with crutches to be faster than their actual speeds. Therefore, using crutches decreased the accuracy of gait imagery and might therefore increase an individual’s risk of falling during walking.     

Postural steadiness and weight distribution during tandem stance in healthy young and elderly adults

BACKGROUND: Tandem stance is a clinical measure of standing balance considered to assess postural steadiness in a heel-to-toe position by a temporal measurement. To our knowledge, no studies have evaluated the change of postural steadiness, expressed as force variability, over time. The objective of this paper is to investigate postural steadiness during 30 s of tandem stance in healthy elderly and young adults, and to explore the weight distribution between legs during tandem stance. METHODS: A cross-sectional analysis comparing ground reaction forces and muscle activity in 26 healthy elderly adults (mean age 70.6 years) and 27 healthy young adults (mean age 30.0 years). Ground reaction forces beneath both feet and muscle activity of ankle muscles were recorded while the subjects performed 30 s of tandem stance during two conditions. FINDINGS: Two phases were identified in both groups: First a dynamic phase, a decrease in force variability during the first 3-4 s after foot placement, and thereafter a static phase, maintaining a certain level of force variability. Age-related changes were seen in the decrease in force variability (P<0.001) and ankle muscle activity (P<0.001). However, both groups placed more weight on the rear leg (P<0.001). INTERPRETATION: The first few seconds of tandem stance pose the greatest challenge to postural steadiness and influence the static phase. We suggest that the dynamic phase is the most crucial period of time for assessing balance requirements. Independent of age, tandem stance is not a task for equal weight bearing.     

Gluteal taping improves hip extension during stance phase of walking following stroke

The aim of this study was to determine whether gluteal taping on the affected side improved hip extension during stance phase of walking for persons following stroke. Fifteen subjects who had suffered a stroke months to years previously resulting in mild to moderate gait impairments participated in the study. Their gait was measured under control, sham, and gluteal taping conditions, in random order. For each condition, subjects walked at a self-selected and a fast speed. Hip angle relative to that obtained during quiet standing, step length, stride length and walking velocity were measured. Hip extension increased significantly with gluteal taping (p < 0.05) for both walking speeds at late stance phase of walk compared to sham taping and control. The mean absolute difference between gluteal and control conditions for self-selected velocity was 14.2 degrees (95% CI 8.6 to 19.8) whereas the difference between sham and control conditions was 2.0 degrees (95% CI -2.0 to 6.0). Also, for both speeds, step length on the unaffected side increased significantly with gluteal taping compared with either the control or placebo conditions. The absolute difference between gluteal taping and control conditions at self-selected velocity was 3.3 cm (95% CI 2.2 to 4.3) and between sham and control conditions was 0.6 cm (95% CI -0.8 to 1.9). Affected step length and walking velocity, however, remained unchanged. Lastly, there was no significant difference between the control and sham taping condition for any of the measured variables. Gluteal taping may be a useful adjunct to current rehabilitation gait training strategies.     

Pharmacokinetics and electrocardiographic effect of ebastine in young versus elderly healthy subjects

The objective of this study was to compare the single- and multiple-dose pharmacokinetics and electrocardiographic effect of a 10-mg oral dose of ebastine in elderly (ages, 65-85 years) and young (ages, 18-35 years) healthy volunteers. Thirty-seven subjects completed this randomized, double-blind, multiple-dose, placebo-controlled, parallel group study. The elderly group consisted of 18 subjects, with 13 subjects receiving 10 mg ebastine and 5 receiving matching placebo. The young group consisted of 19 subjects, with 13 subjects receiving 10 mg ebastine and 6 receiving matching placebo. On study days 1 and 3 through 10, each subject received a single 10-mg dose of ebastine or matching placebo in the morning with a standard breakfast. No drug was administered on study day 2 because of pharmacokinetic sampling. Blood samples were collected at selected times postdose on study days 1, 2, and 10. Plasma samples were analyzed for ebastine and its active metabolite, carebastine, using a validated high-performance liquid chromatography method. No plasma ebastine concentrations were detected, suggesting essentially complete metabolic conversion of ebastine to its metabolites. Analysis of variance showed no statistically significant differences between young and elderly single- and multiple-dose carebastine pharmacokinetics with respect to area under the plasma concentration-time curve, maximum concentration (Cmax ), terminal elimination rate constant, apparent oral clearance, or apparent volume of distribution. The mean time of maximum concentration value for young subjects was 1 hour longer than that for elderly subjects after single-dose administration but was comparable after multiple-dose administration. Within-group comparisons of both the young and elderly showed that pharmacokinetics between single dose and steady state were not statistically different. However, the mean steady-state carebastine Cmax values were approximately twofold greater than the mean Cmax values obtained after single-dose administration. A twofold increase in Cmax values between single-dose and steady-state administration is predicted for drugs such as carebastine, because its input interval is approximately equal to its elimination half-life. Twelve-lead electrocardiography was performed before dosing on day 1 and repeated 4 hours postdose on days 1, 5, and 10. Twenty-four hour Holter monitoring was also performed before and at the end of the study. No clinically relevant findings were found by electrocardiography or Holter monitoring between ebastine and placebo in the elderly and young subjects.     

The effects of cognitive tasks on the frequency of non-MTC gait cycle during walking in healthy older and young adults

[Purpose] To investigate the effects of cognitive tasks on the non-minimum toe clearance gait cycles (nMTC) frequency during walking in healthy older and young adults. [Participants and Methods] This study included 20 healthy older and 20 young adults. The participants performed 3 min preferred-speed walking under a single-task and three dual-tasks (DTs) consisting of verbal, subtraction, and recall tasks. We determined the nMTC, which could not detect a trough in the toe trajectory during the swing phase. We evaluated the nMTC frequency (the cases of nMTC / total gait cycles) and compared them among the tasks and between groups. [Results] The results of the two-way analysis of variance revealed that there were no differences among the tasks, while the nMTC frequency in the older group was higher than that in the young group. The DT cost (DTc), which was used as an indicator of cognitive-motor interference (CMI), was higher in the subtraction and recall tasks in the older group than those in the young group. [Conclusion] This study showed that adding a cognitive task while walking increased in the nMTC frequency in older adults. These results suggest that the nMTC frequency under DT would reflect the increased CMI in healthy older adults.     

Kinematic, kinetic and metabolic parameters of treadmill versus overground walking in healthy older adults

Background

Although treadmill and overground walking appear to be biomechanically similar in healthy, young adults it is not known whether this can be generalized to older subjects or if the metabolic demands are correspondingly comparable.

Methods

Ten healthy adults between 50 and 73 years of age walked at the same speed overground and on a treadmill. Temporal parameters, angular kinematics and vertical ground reaction forces were recorded during walking once subjects were in steady state as determined from their heart rate and oxygen uptake.

Findings

Step, stride and joint angular kinematics were similar for both modes of walking with the exception of the maximum hip flexion and knee extension which were more pronounced with treadmill or overground walking, respectively but in both instances differed by less than 3°. Vertical ground reaction force profiles were similar although the peak associated with push-off was 5.5% smaller with treadmill walking. The metabolic requirements of treadmill walking were about 23% higher than that associated with overground walking.

Interpretation

While treadmill and overground walking are biomechanically similar, the metabolic cost of treadmill walking is higher. Clinically this may be important when using a treadmill for gait retraining in patient populations as it may lead to premature fatigue or undesirable physiologic challenge.     

不同年龄健康人群步行能量消耗特点研究

目的 探讨年龄与性别在健康人群不同步行速度下对体力活动能量消耗量(AEE)的影响,以及在同一速度下快走与慢跑两种运动方式的AEE特点.方法 共选择60名受测者(20～50岁),根据性别分为男、女两组,每组30名,每组再根据年龄分为3个亚组,即20～30岁、31～40岁和41～50岁组,每亚组10人.采用气体代谢仪测量以3.5、4.5、5.5 km/h行走和以5.5、6.5、7.5 km/h跑步的AEE,其结果进行统计学比较.结果 同一年龄段,男性与女性在不同速度下的AEE比较,差异均无统计学意义(P＞0.05);各组在不同行走速度下 AEE值组间比较,差异均有统计学意义,其中以4.5 km/h速度行走的31～40岁女性AEE均高于21～30岁女性和男性及41～50岁女性,21～30岁女性AEE低于41～50岁男性(P＜0.05);以7.5 km/h速度慢跑的21～30岁男性AEE高于 41～50岁女性(P＜0.05);以5.5 km/h速度快走与慢跑时,除了41～50岁男性组外,其余各组AEE比较,差异均有统计学意义(P＜0.05).结论 随着步行速度的增长,各组AEE均增高,在行走时41～50岁人群AEE较21～30岁人群高,但在跑步时21～30岁人群AEE增长较快,31～40岁女性无论步行还是跑步时AEE均较高;性别对AEE的影响较年龄小;在相同时间、同一速度且无额外负荷的前提下,慢跑比快走消耗的能量更多.

Abstract：

Objective To measure the activity energy expenditure(AEE) of healthy adults during level walking by using indirect calorimetry,and to analyze the characteristics and underlying influencing factors such as age and gender. Methods A total of 60 healthy adults aged 20-50 years (30 males and 30 femdes) participated in the study.All the subjects were divided into six groups by gender and age (the age span of each group was 10 years). The subjects were arranged to walk at speeds of 3.5,4.5,5.5km/h and run at 5.5,6.5,7.5km/h, respectively, on the treadmill. The resting energy expenditure ( REE ) and AEE were measured during walking and running at different speeds.There was a 5-minute rest among the test sessions. Results No difference in terms of AEE between the female and male at the same age ( P ＞ 0. 05 ). During 3.5km/h walking,AEE of 21-30 year-old females was lower than 31-40 yearold females and males( P ＜0.05 ) ;During 4.5km/h walking,AEE of 31-40 year-old females was higher than 21-30 yearold females and males and 41-50 year-old females; AEE of 21-30 year-old females was lower than 41-50 year-old males (P ＜ 0.05 ) ;During 5.5km/h walking,AEE of 31-40 year-old females was higher than 21-30 year-old females and males ( P ＜ 0. 05 ). During 6.5 km/h running, AEE of 31-40 year-old females was higher than 41-50 year-old females ( P ＜0.05), while during 7.5km/h running, AEE of 21-30 year-old males was higher than 41-50 year-old females (P ＜0.05 ). It was also found that the AEE of all groups except the 41-50 year-old females group was higher when walking at the speed of 5.5km/h than running at the same speed( P ＜ 0.05 ). Conclusions Age has more effect on REE and AEE than the gender. AEE of elder subjects is higher than that of the younger ones during walking, however, AEE of younger people increases faster than the elders during running. AEE of 31-40 year-old females is the highest in all groups both in walking and running. AEE in running is higher than in walking at the same speed.     

Identification of healthy elderly fallers and non-fallers by gait analysis under dual-task conditions

OBJECTIVE: We compared falling and non-falling healthy elderly subjects to identify balance disorders associated with falling. Gait parameters were determined when carrying out single and dual tasks. DESIGN: Case comparison study. SETTING: Subjects were studied in the gait laboratory at H?pital Roger Salengro, Lille, France. SUBJECTS: A group of 40 healthy elderly women were assigned to one of two groups according to their falling history: 21 fallers aged 70.4 +/- 6.4 years and 19 non-fallers aged 67.0 +/- 4.8 years. All subjects performed first a single leg balance test with two conditions (eyes open/closed). Then, gait parameters were analysed under single-task and dual motor-task conditions (walking with a glass of water in the hand). MAIN MEASURES: Falls, number of times suspended foot touched the floor during the single leg balance test, cadence, speed, stride time, step time, single-support time, stride length and step length during walking under single- and dual-task conditions. RESULTS: During the single leg balance test, fallers placed their feet on the floor three times more often than non-fallers under eyes open conditions (P < 0.05) and twice as often under eyes closed conditions (P < 0.05). In the single-task condition, no significant difference in gait parameters was reported between fallers and non-fallers. There was a significant difference (P < 0.05) in the gait parameters (cadence, speed, stride and step time, single-support time) between fallers and non-fallers under dual-task conditions. CONCLUSIONS: Dual tasks perturb walking in fallers, who exhibit deteriorated static balance. Consequently, walking under dual-task conditions plus a single leg balance test could be helpful in detecting walking disorders and planning physiotherapy to prevent falls.     

Toe clearance and velocity profiles of young and elderly during walking on sloped surfaces

Background  

Most falls in older adults are reported during locomotion and tripping has been identified as a major cause of falls. Challenging environments (e.g., walking on slopes) are potential interventions for maintaining balance and gait skills. The aims of this study were: 1) to investigate whether or not distributions of two important gait variables [minimum toe clearance (MTC) and foot velocity at MTC (Vel_MTC)] and locomotor control strategies are altered during walking on sloped surfaces, and 2) if altered, are they maintained at two groups (young and elderly female groups).     

The effect of a dual-task on obstacle crossing in healthy elderly and young adults

OBJECTIVE: To investigate the effect of a dual-task on step initiation over an obstacle. DESIGN: Repeated-measures design between groups. SETTING: University laboratory. PARTICIPANTS: Ten healthy, community-dwelling elderly adults and 10 healthy young adults. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The effect of a reaction time task on ground reaction forces, toe clearance, and temporal events in stepping over an obstacle. RESULTS: Ground reaction forces of the swing limb before toe-off did not differ between the groups and was not affected by task difficulty. Stepping with a random stimulus after toe-off was the most difficult task, whereas stepping with a predictable stimulus before toe-off was the easiest task. Reaction time and stepping time were greater and toe clearance was less for the elderly subjects. Both groups had a decrease in toe clearance and an increase in reaction time and stepping time as the task became more difficult. CONCLUSIONS: Our findings indicate that even healthy older adults may be at risk for falls in situations where they are engaged in concurrent tasks. The data support the inclusion of dual-task activities in fall prevention programs.     

Home postural evaluation in the elderly: comparison between fallers and non fallers]

OBJECTIVES: To determine the main clinical and posturographic factors correlated with falls in elderly individuals and to specify the role of static posturography in this appraisal. MATERIALS AND METHODS: The study involved 38 people living in an residential center who were autonomously ambulatory and had a Mini Mental Test score> or =24. Fallers (N = 15) had fallen within 1 month, and nonfallers (N = 23) had not fallen for at least a year. Assessment consisted of a series of questions, a complete clinical appraisal, specific independently validated tests, and static posturographic analysis different parameters of the stabilogram with the eyes first open and then closed, all carried out in the center. RESULTS: From the clinical standpoint, spinal pathologic features and the scores on the Functional Reach Test were significantly different between the fallers and nonfallers. In static posturography, fallers' equilibrium was more precarious than that of nonfallers with eyes are closed: significant differences were observed in surface, X length and overall fast Fourier transform score. The comparison between results with open and closed eyes showed that the fallers had a pronounced tendency to retropulsion in the absence of visual participation: a significant difference as regards overall length, Y length, minimum Y and FFT Y (0.5-2 Hz). CONCLUSIONS: To complement a satisfactorily conducted clinical examination, static posturography allows for rapid assessment of equilibrium and posture in elderly patients who fall? Performed at the place where an individual resides, this appraisal constitutes an original and pragmatic element. As an evaluation strategy, it can reveal nonnegligible information within the framework of an appraisal of such, and thereby allows for adjustment of the rehabilitation or compensatory strategy.     

Control of the upper body accelerations in young and elderly women during level walking

Background  

The control of the head movements during walking allows for the stabilisation of the optic flow, for a more effective processing of the vestibular system signals, and for the consequent control of equilibrium.     

Frequency domain characteristics of ground reaction forces during walking of young and elderly females

OBJECTIVE: To examine the frequency domain characteristics of the ground reaction forces of young and elderly females during free walking. DESIGN: Independent t-tests were used to examine the frequency content of all three components of the ground reaction force. BACKGROUND: Frequency domain analysis has the potential to assist in identifying changes in gait that may be masked in the time domain. No research has been done to identify changes in gait due to age-related impairments in the frequency domain. METHODS: Ten young and ten elderly females walked at a prescribed speed while ground reaction forces were collected via a force platform. The highest frequency required to reconstruct the 99% of the signal's power in each direction was calculated from the ground reaction forces. RESULTS: The frequency content significantly decreased in the anterior-posterior direction for the young group. No significant differences were found for the other two directions (vertical and mediolateral) between the two groups. The elderly had a significantly higher frequency content compared with the young in the anterior-posterior direction. CONCLUSIONS: Ageing differences were detected using the frequency domain analysis for the anterior-posterior direction. It is possible that these differences were the result of the decrease in walking speed associated with the elderly group. RELEVANCE: Frequency domain analysis of the ground reaction forces is a useful addition to the gait analyst's armamentarium especially when such changes are not obvious in the time domain.     

Attention demanding tasks during treadmill walking reduce step width variability in young adults

Background

The variability of step time and step width is associated with falls by older adults. Further, step time is significantly influenced when performing attention demanding tasks while walking. Without exception, step time variability has been reported to increase in normal and pathologically aging older adults. Because of the role of step width in managing frontal plane dynamic stability, documenting the influence of attention-demanding tasks on step width variability may provide insight to events that can disturb dynamic stability during locomotion and increase fall risk. Preliminary evidence suggests performance of an attention demanding task significantly decreases step width variability of young adults walking on a treadmill. The purpose of the present study was to confirm or refute this finding by characterizing the extent and direction of the effects of a widely used attention demanding task (Stroop test) on the step width variability of young adults walking on a motorized treadmill.

Methods

Fifteen healthy young adults walked on a motorized treadmill at a self-selected velocity for 10 minutes under two conditions; without performing an attention demanding task and while performing the Stroop test. Step width of continuous and consecutive steps during the collection was derived from the data recorded using a motion capture system. Step width variability was computed as the standard deviation of all recorded steps.

Results

Step width decreased four percent during performance of the Stroop test but the effect was not significant (p = 0.10). In contrast, the 16 percent decrease in step width variability during the Stroop test condition was significant (p = 0.029).

Conclusion

The results support those of our previous work in which a different attention demanding task also decreased step width variability of young subjects while walking on a treadmill. The decreased step width variability observed while performing an attention demanding task during treadmill walking may reflect a voluntary gait adaptation toward a more conservative gait pattern emphasizing frontal plane control of the trunk. Extension of the experimental paradigm to older adults and mechanistic approaches to link step width variability to dynamic stability, and falls, in a cause-effect manner are necessary.     

Lumbofemoral rhythm during active hip flexion in standing in healthy older adults

The 2D PEAK Motus motion analysis system was used to measure the sagittal lumbofemoral rhythm during active hip (knee) flexion in standing in 34 healthy older adults whose movement may be influenced by age-related changes in the neuromusculoskeletal system. When the thigh was raised, the lumbar spine moved concurrently with the hip joint throughout the movement. Approximately 5° of initial hip flexion occurred before 1° of lumbar flexion. Overall, the lumbar spine contributed 26.6% (29.3°) of the total thigh movement (pelvis + hip joint) during the upward (110.2°) movement phase. Compared to children and young adults, older adults demonstrated some age-related differences in sagittal lumbofemoral rhythm, including decreased hip flexion and a large variation in the hip-to-lumbar movement ratio. Clinicians and exercise instructors need to be aware of the concurrent movement interaction between the hip joint and lumbar spine when measuring hip flexion range or when instructing abdominal, hip, or lumbar exercises. The potential influence of limited range of motion of either hip or lumbar component on the movement should also be addressed.     

Relationship between single-leg stance test with light touch and hip muscle strength in healthy young adults

[Purpose] This study investigated the relationship between the single-leg stance test with light touch and hip rotator muscle strength. [Participants and Methods] Thirty-one healthy young adults participated in the study. A single leg stance test with light touch was performed to evaluate the participants’ static balance ability. The duration that an individual could successfully perform the single leg stance test with light touch in the eyes open was measured. The participants were instructed to slightly touch their right index fingertip on the digital scale. The hip muscle strength of the internal rotators and external rotators were measured by the isometric peak torque. The internal/external rotator strength ratio was calculated by dividing the strength of the internal rotator by that of the external rotator. [Results] The hip external rotator muscle strength was higher in males than in females. Moreover, there was a significant correlation between the single-leg stance test with light touch and hip external rotator muscle strength in males and between the single leg stance test with light touch and hip internal rotator muscle strength in females. Furthermore, a significant positive correlation was found between the single leg stance test with light touch and hip internal rotator/external rotator ratio in males. [Conclusion] We concluded that the single leg stance test with light touch is a useful tool to evaluate static hip muscle strength.Key words: Hip rotator cuff, Hip stability, LT-SLST     

Comparison of urinary excretion of four lysosomal hydrolases in healthy elderly and young adults.

The activities of four lysosomal enzymes and creatinine levels were measured in the plasma and urine of 17 healthy elderly and 7 young adults. Fractional enzyme excretion (FE ENZ) values for beta-hexosaminidase (N-acetylglucosaminidase), alpha-galactosidase, beta-galactosidase and beta-glucuronidase were calculated and compared between the two groups of subjects. FE ENZ was calculated as the ratio of enzyme clearance to creatinine clearance. The FE ENZ values for alpha-galactosidase, beta-galactosidase and beta-glucuronidase between the elderly and young populations were not statistically different; however, relative to the young control group, the FE ENZ value for beta-hexosaminidase was elevated approximately 2-fold in the elderly population (P = 0.06). The mean urinary alpha-galactosidase activity for the elderly population, when expressed on the basis of creatinine, was 50% lower than that of the control group (P = 0.03), whereas the mean urinary beta-hexosaminidase activity for the elderly was significantly higher compared to the control group (P = 0.008). When data for all subjects was analyzed, no correlation was observed between the urinary excretion of beta-hexosaminidase or alpha-galactosidase and glomerular filtration rate. These data indicate that with advancing age there are changes in the tubular secretion or reabsorption of selective lysosomal enzymes, particularly beta-hexosaminidase and alpha-galactosidase. These biochemical changes may provide a means of assessing subtle progressive deterioration of renal function.