Physical function improvements after laparoscopic Roux-en-Y gastric bypass surgery

Abstract

Background:

Obesity is a risk factor for impaired physical function and disability, with the degree of impairment most compromised in extreme obesity. Mild-to-moderate weight loss has been shown to improve function in older adults. The impact of laparoscopic Roux-en-Y gastric bypass surgery on weight loss and physical function in morbidly obese individuals was assessed.

Methods:

This longitudinal, observational study followed up 28 morbidly obese men and women (body mass index ≥40.0 kg/m²) for 12 months after laparoscopic Roux-en-Y gastric bypass. Physical function (self-report using the Fitness Arthritis and Seniors Trial disability questionnaire; performance tasks using the Short Physical Performance Battery and a lateral mobility task); strength (maximal isometric knee torque); and body composition measured using bioelectrical impedance were determined before surgery (baseline) and at 3 weeks, 3 months, 6 months, and 12 months after surgery.

Results:

The 12-month weight loss was 34.2% (excess weight loss 59.8%), with a mean fat mass loss of 46 kg and a loss of fat free mass of 6.6 kg. The performance tasks and self-reported questionnaire scores had improved by 3 months after surgery compared with baseline, with selected measures showing less impairment and disability in as few as 3 weeks after surgery. Muscle quality, as measured using the maximal torque per kilogram body weight, was greater at 6 months than at baseline.

Conclusion:

The results of our study have shown that in morbidly obese individuals with a high risk of mobility impairments, surgical procedures to reduce body weight increase mobility and improve performance of daily activities in as few as 3 weeks after gastric bypass surgery.

The prevalence of obesity continues to increase in the United States and worldwide. Excess body fat is associated with many health concerns, notably impairments in physical function and mobility. As expected, the rates of these impairments are also increasing; this is especially apparent for those <65 years [1]. A recent survey showed that 16% of adults >18 years reported having a functional limitation, with nearly 10% indicating that they had trouble climbing a flight of stairs or walking 3 city blocks [2]. Data from cross-sectional studies have provided evidence that obesity is related to detriments in physical function, physical performance, and disability, with the degree of impairment most compromised in those with extreme obesity [3–6].

The use of traditional dietary and exercise behavioral therapies for treating extreme obesity has shown limited long-term success. An alternative to these modest outcomes is surgical intervention, because bariatric procedures have been shown to produce substantial weight loss. A recent meta-analysis showed an average of 61.2% of excess weight was lost across all surgery types for at least 1 year of follow-up, with 68.2% excess weight loss occurring after gastric bypass procedures, including Roux-en-Y gastric bypass (RYGB) [7]. Although obesity is a major risk factor for mobility disability and physical impairments, no studies have assessed the effect of extreme weight loss after bariatric surgery on performance-based physical function measures. Earlier work by our group demonstrated that modest weight loss of 5–10% improved functional measures in obese and overweight older adults with osteoarthritis of the knee [8,9]. Therefore, the primary aim of the present observational pilot study was to investigate the effect of laparoscopic RYGB on performance and self-report based on physical function in those with extreme obesity. In addition, alterations in total body composition (i.e., fat and fat free mass and muscle strength) were studied. It has been hypothesized that the surgery and accompanying weight loss will lead to an improvement in mobility in this population. The hypothesis for the second aim was that in the absence of a formal exercise training program, the fat free mass and absolute muscle strength will decline with extreme weight loss.

Methods

Study population

A total of 28 patients were recruited from the general surgery clinic scheduled for laparoscopic RYGB (A.F., surgeon) at Wake Forest University Baptist Medical Center. The eligibility criteria for the proposed pilot study included men and women with a body mass index (BMI) ≥40.0 kg/m² or ≥35.0 kg/m² with an obesity-related co-morbidity, such as diabetes, hypertension, or dyslipidemia. In addition, participants had to have reported a sedentary lifestyle (not >20 minutes of structured exercise on ≤2 d/wk) and to have self-reported difficulty in performing ≥1 of the following activities attributed to back, hip, knee, or ankle pain: lifting and carrying groceries, walking one-quarter mile, getting in and out of a chair, or going up and down stairs. Study participants met with the surgeon and clinic staff and were scheduled for surgery before learning about and being recruited for the study. All clinic patients who met these eligibility criteria were given the option to participate in the study. Study recruitment occurred during a 15-month period. No apparent selection biases were present in the study recruitment.

We certified that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during this research. The institutional review board of Wake Forest University approved the study. Staff from the general surgery clinic obtained consent for study participation and acquired the demographic information and health history from the patients. Measurements of physical function, strength, and anthropometrics were performed by trained staff at the Geriatric Research Center and the Geriatric General Clinical Research Center. These data were obtained at baseline (before surgery) and at 3 weeks, 3 months, 6 months, and 12 months after surgery.

Outcome measures

The patients’ weight and height were measured using standard techniques. In brief, the weight and height were determined with the patients’ shoes and jackets or outer garments removed. The instruments were calibrated on a weekly basis. The BMI was calculated from these measures with the weight in kilograms, divided by the height in squared meters. The amount of excess weight was obtained by subtracting the actual weight from the ideal weight, determined using the National Institute of Diabetes, Digestive, and Kidney Disease standard height and weight table for adults according to gender [10].

The battery of tests for physical function included the use of self-report questionnaires and performance tasks.

Self-reported physical function was measured using the modified Fitness Arthritis and Seniors Trial (FAST) Disability questionnaire [11]. This survey uses 23 questions directed toward assessing self-reported difficulties in performing physical tasks required for daily living. The questionnaire is not specific to a certain disease and queries about perceived difficulties in general activities of daily living during the previous month. The respondents answer for each of the items whether they experience no difficulty, a little difficulty, some difficulty, a lot of difficulty, unable to do, or did not do for other reasons. This instrument provides distinct dimensions in the basic activities of daily living (e.g., dressing one’s self), complex instrumental activities of daily living (e.g., doing light housework), ambulation and climbing (e.g., climbing stairs), transfer (e.g., getting into and out of a car), and upper extremity strength (e.g., lifting heavy objects).

Performance tasks are tests that provide objective measurements of mobility disability. The tests we used were the Short Physical Performance Battery (SPPB) and lateral mobility.

The SPPB is a composite of 3 separate tests: balance, walking time, and chair rise time. Each test is scored on a 0–4 scale, with 0 being unable to perform and 4 representing maximal performance. This battery of tests was developed from the Established Populations for the Epidemio-logic Study of the Elderly cohort [12]. It has been shown to be a good predictor of disability risk according to age, gender, and level of performance. For balance tests, the participants attempted to hold their balance for 10 s in different standing positions—side by side, semitandem, and tandem. The side by side was performed initially. If they held that position for 10 s, they received 1 point. They were then challenged to hold a semitandem position (heel of 1 foot immediately in front of the big toe of the second foot). Two points were rewarded if they held that position for 10 s. The participants then advanced to the full tandem position; if they held this position for 10 s, they received 4 points; if they held the full tandem for 3–9 s, they earned 3 points, if they held it for ≤2 s, they earned 2 points.

Walking time was assessed over a 4-m distance. The participants were instructed to walk as though they were heading to a store. They had 2 trials, with the time on the faster of the 2 walks used for scoring: score of 1, time of ≥8.7 s; score of 2, 6.21–8.70 s; score of 3, 4.82–6.20 s; and score of 4, ≤4.81 s.

The procedure for the chair rise included having the participants sit in a straight-back chair without arm rests and placed against the wall. With arms folded across their chest, they were asked to stand up. If they could not stand up without using their arms, their score was 0. If they could stand up, they repeated it 5 times as quickly as possible. The score was 1 for a time of ≥16.70 s; score of 2 for 13.70–16.69 s; score of 3 for 11.20–13.69 s; and score of 4: ≤11.19 s.

A total SPPB score was then calculated by summing the categorical rankings for the performance on each of the 3 tests—balance, walking time, and chair rise time. The total score has a good internal consistency (Cronbach’s α = .76)[12]. Additionally, because the chair rise and walking time tasks of the SPPB are on a continuum scale, the change in the time to complete these tests was also assessed and analyzed separately from the total SPPB score. The SPPB has been used in a variety of research studies to assess physical function and has correlated strongly with self-reported disability and an independent predictor of short-term mortality and nursing home admission in older adults (age ≥71 years) [12,13].

The lateral mobility task mimics the movement of getting in and out of a car [14]. It is a dynamic action in which the center of gravity is moving laterally and the base of support also moves. The task measures the ability of an individual to transfer from 1 position to another. The time to complete this functional performance test correlates with other measures of function and strength (r = −.33 to −.45), such that a faster time is related to greater function and increased strength. In this timed task, the participant steps across an 18-cm crossbar, ducks under a 128-cm crossbar, and then sits down in a chair with their feet raised on a step at 20.5-cm high. Three trials are completed, with the fastest trial used in the analysis.

To evaluate the body composition, the fat mass and lean body mass, in both absolute and relative amounts, were determined using bioelectrical impedance assessment (RJL Quantum II Desktop, Clinton Township, MI). This method has been validated and used previously in morbidly obese populations [15,16]. The participants are placed in the supine position for the measurement.

Unilateral quadriceps strength was assessed as the torque produced during a maximal voluntary isometric contraction using an isometric dynamometer (Litek Isometric Chair, Bio Logic Engineering, Dexter, MI). The participants were seated in a fully adjustable chair with their knees flexed at 90°. They were asked to attempt to extend one knee (knee extension), pushing as hard as they could against the dynamometer, which was positioned a few inches above the ankle. A shin pad was then strapped over the lower leg with the heel resting in the trolley. Three trials were performed on each leg. Strength was assessed as the peak torque, expressed in Newton-meters, recorded during a 4-s effort.

Statistical analysis

Repeated measures analysis of covariance was used to assess the changes in functional outcomes, weight, and body composition during the follow-up period. Estimated marginal means are presented from the analysis. The covariates in the model were age, gender, and initial BMI. Differences were deemed significant at P ≤.05. Pearson product correlations were performed for determining relationships between body weight parameters and function at baseline and with the 12-month changes in body weight and the 12-month changes in physical function. All analyses were performed using the Statistical Package for Social Sciences, version 15.0 (SPSS, Chicago, IL).

Results

A total of 28 participants agreed to participate in the study and underwent baseline visits, with 27 undergoing surgery. During the study period, 6 serious adverse events occurred in 3 different participants; none of the events were the result of the study’s testing procedures. The serious adverse events included 3 hospitalizations for 1 patient (appendectomy, infiltrated intravenous site, and chest pain), 2 hospitalizations for 1 patient (nausea, vomiting, dehydration, and ulcer at gastrojejunal anastomosis), and 1 hospitalization for 1 patient (hypokalemia and dehydration secondary to influenza). Six participants withdrew from the study (including 2 of the 3 with serious adverse events) and were lost to all or some part of the follow-up testing. The reasons for withdrawing from the study included surgical complications, no longer being followed up by the surgeon, and personal (lack of time and no child care). Of the 28 participants at baseline, 26 were women and 25 were white. The average age was 43.5 years, with the youngest 27.1 years and the oldest 59.1 years. The top 6 most common co-morbidities included degenerative joint disease (92.9%), hypertension (67.9%), gastroesophageal reflux disease (67.9%), dyslipidemia (53.6%), depression(53.6%), and sleep apnea (50.0%).

At baseline, the body weight was 145.6 ± 5.0 kg (range98.3–207.4). The calculated excess weight was 88.0 ± 4.4 kg. The initial BMI was 53.0 ± 1.6 kg/m², with a percentage of body fat of 63.7% ± .5% and percentage of fat free mass of 36.3% ± .5%.

During the 12-month follow-up period, repeated measures analysis of variance showed significant differences in body weight at each of the postoperative points compared with baseline (Fig. 1). Greater weight loss had occurred in absolute and relative terms (percentage of weight loss and percentage of excess weight loss) at each point compared with the previous collection period throughout the 12-month follow-up period (Fig. 2). The percentage of weight loss was −7.8% at 3 weeks, −17.5% at 3 months, −26.2% at 6 months, and −34.2% at 12 months (Fig. 2A). The percentage of excess weight loss was −14.1% at 3 weeks, −31.5% at 3 months, −46.5% at 6 months, and −59.8% at 12 months (Fig. 2B). The BMI decreased from 53.0 ± 1.6 kg/m² at baseline (n = 20) to 34.8 ± 1.3 kg/m². By the end of the study, the body fat percentage had decreased from63.7% to 51.3%, a loss of >46 kg of fat. A greater amount of fat loss was apparent at each subsequent point after 3 weeks, although no difference was found between baseline and 3 weeks for the percentage of body fat. The relative fat free mass increased from 36.3% to 48.7%, and the absolute fat free mass decreased from 57.2 ± 1.7 to 50.6 ± 1.3 kg.

Fig. 1.

Body weight during 12-month follow-up. Data presented as estimated marginal means with standard error of mean (n = 19).

Fig. 2.

Relative weight loss as percentage of (A) total weight and (B) excess weight. Data presented as estimated marginal means with standard error of mean (n = 19).

Physical performance was assessed with the SPPB using balance, walking time, and chair rise tasks, and the lateral mobility task. Significant improvements in the total SPPB score were apparent by 3 months compared with baseline and the 3-week values and continued throughout the remaining points (Table 1). The score for the battery of tests was 9.1 ± .4 at baseline and had improved to 11.1 ± .3 at 12 months, a 21.8% improvement. Statistically significant differences were also apparent between 3 and 12 months and between 6 and 12 months. Figure 3 demonstrates the percentage of change from baseline in the total SPPB score. A 10% increase in score was shown at 3 weeks, with an additional 26.2% increase in the score apparent at 12 months. Because gait speed and chair rise time are on a continuous scale, the changes in actual time to complete the task were analyzed separately. The walking time for the 4-m distance decreased from 5.41 ± .77 s at baseline to 3.87 ± .33 s after 1 year of weight loss (Table 1), with faster times seen at each point compared with baseline. A faster gait speed was found between 3 weeks and each other point and for 3 months compared with 12 months, although no differences were observed between 3 and 6 months or 6 and 12 months. The chair stand time also improved from 15.90 ± .90 s to 12.08 ± .98 s at 12 months. Differences from baseline were observed at 3, 6, and 12 months (Table 1). Furthermore, the 3-week and 3-month measurements differed from their subsequent follow-up periods, but no additional improvement was observed between 6 and 12 months. The percentages of change in these variables from baseline to each of the points are shown in Figure 4. Both gait speed and chair rise time improved by 20% between baseline and 12 months.

Table 1.

Physical function measures at baseline and 3 weeks and 3, 6, and 12 months postoperatively

Measure	Baseline	3 wk	3 mo	6 mo	12 mo
Total SPPB score (n = 18)	9.1 ± .4	9.4 ± .5	10.2 ± .5*	10.3 ± .5*	11.1 ± .3*
Chair stand time (s) (n = 18)	15.90 ± .90	15.33 ± 1.31	14.01 ± .99*	12.47 ± .68*	12.08 ± .98*
4-m Walking time (s) (n = 18)	5.41 ± .77	4.83 ± .56*	4.45 ± .58*	4.24 ± .57*	3.87 ± .33*
FAST disability questionnaire score (n = 19)	2.2 ± .2	1.9 ± .2†	1.5 ± .2*	1.5 ± .2*	1.3 ± .1*
Lateral mobility (s) (n = 14)	6.00 ± .64	5.28 ± .48*	4.41 ± .30*	4.03 ± .25*	3.88 ± .18*
Maximal torque (Nm) (n = 16)	126.3 ± 1.8	113.2 ± 8.3	108.5 ± 7.1	111.7 ± 9.2*	97.7 ± 7.9*
Maximal torque/kg body weight (Nm/kg) (n = 16)	.87 ± .07	.87 ± .07	.93 ± .07	1.06 ± .08*	1.03 ± .08‡

SPPB = Short Physical Performance Battery; FAST = Fitness Arthritis and Seniors Trial.

Data presented as estimated mean ± standard error of mean.

^*Significantly different from baseline measure (P <.05).

^†P = .098 between baseline and 3-week point.

^‡P = .057 between baseline and 12-month point.

Fig. 3.

Percentage of changes from baseline in SPPB and FAST physical function measures across 12-month follow-up period. Data presented as estimated marginal means with standard error of mean (n = 19).

Fig. 4.

Percentage of changes from baseline in gait speed, chair rise time, lateral mobility time, and maximal torque across 12-month follow-up period. Data presented as estimated marginal means with standard error of mean (n = 19).

The lateral mobility task showed rapid improvements during follow-up, with significant differences from baseline to 3 weeks, which continued throughout the study (Table 1). At baseline, the task was completed in a mean time of 6.0 ± .64 s. By 3 weeks postoperatively, the time had decreased .72 s to 5.28 ± .48 s. At 12 months, it took only 3.88 ± .18 s for patients to perform the test. In comparing the times at other points, a subsequent decrease occurred in the time to complete the task from 1 period to the next, except for between 6 and 12 months, when no additional improvement was noted. The data presented in Figure 4 demonstrate the relative improvement compared with baseline for this task. Even at 3 weeks, the time to complete the task had improved by 12.9%, with a steady improvement at each point, including a >50% faster time by 12 months.

The self-reported FAST disability questionnaire score was 2.2 ± .2 at baseline. Significant improvements were seen at 3, 6, and 12 months compared with baseline (Table 1). A strong trend was noted for improvement in this instrument at the 3-week measurement (P = .098), but this did not achieve statistical significance. In addition, the values at 3 weeks were different from those at subsequent measurements, and the 3-month FAST score was different than that at 12 months, but not at 6 months. No additional improvement was seen in the self-reported function between 6 and 12 months. This measure showed the greatest percentage of improvement across the observation period, reaching nearly 70% by 12 months (Fig. 3).

The maximal torque expressed on an absolute basis (Newton-meters) in the isometric knee strength test did not differ at 3 weeks or 3 months compared with baseline, although at 6 and 12 months, a decrease in torque was noted compared with the baseline values, reaching a low of 97.7 ± 7.9 Nm at 12 months (Table 1). This is additionally demonstrated on a percent change scale in Figure 4. However, when expressed on a relative scale (Newton-meters per kilogram body weight) as an indicator of muscle quality, the maximal torque values improved from .87 ± .07 Nm/kg body weight at baseline and 3 weeks to 1.06 ± .08 Nm/kg at 6 months, with a strong trend (P = .057) for significant improvement at 12 months, with a mean value of 1.03 ± .08 Nm/kg body weight. Normalizing the data for fat free mass showed no differences among the follow-up points (data not shown).

Pearson correlations were performed between the physical function measures at baseline and the BMI, body weight, excess body weight, and percentage of body fat. No statistically significant associations were found among the variables (data not shown). Similarly, no correlations were found between the changes in the weight parameters and physical function or strength changes from baseline to 12 months (data not shown).

Discussion

The study’s primary purpose was to examine physical function in morbidly obese individuals after laparoscopic RYGB surgery, with a secondary aim of assessing body composition and muscle strength changes. Improvements were observed in all function measures, including performance tasks and self-reported questionnaires. These measures provided different challenges to participants and mimicked a variety of daily activities. Better function for each test battery was apparent after surgery. Additionally, significant improvements were found from baseline in as little as 3 months for all measures, with a change in lateral mobility seen in as few as 3 weeks postoperatively. The total score for SPPB, lateral mobility task time, and FAST improved 26.1%, 51.2%, and 67.9% (estimated marginal means), respectively, between baseline and 12 months postoperatively.

Because of the public health issue of obesity and physical function impairments, it is surprising that few studies have examined weight loss in the context of physical function changes. These findings have consistently shown that modest weight loss, in conjunction with exercise training, improves physical function in both younger and older adults [8,17–24]. In contrast, the use of energy-restricted diets alone for weight loss has not previously shown benefits in muscle strength or performance tasks [9,25]. These earlier studies suggested that exercise training is needed, in conjunction with mild weight loss, to improve physical function. In contrast, we found improvements in physical function without exercise training. However, we speculate that additional improvements through increases in strength and preservation of the fat free mass could be achieved by incorporating structured exercise training into the treatment program.

In community-dwelling older adults, an increase in the SPPB score by .5 point is considered a small meaningful change. In contrast, a substantial change is a ≥1 point increase in the total score [26]. Considering that the SPPB increase in the present study was nearly 2 points, the improvements stemming from the massive weight loss would be considered greater than substantial. However, one must consider that the original work for this was performed in older adults compared with the younger cohort used in this study. It is uncertain whether the same scale for improvement is applicable to our population.

Although most performance measures used in the present study involved anterior movement of the center of gravity, the lateral mobility task differed in that it required lateral changes of the center of gravity. This simple test simulates an instrumental activity of daily living (i.e. getting in and out of a car). In older adults, the inability to perform an instrumental activity of daily living is nearly 3 times more likely to occur with a BMI >35.0 kg/m² compared with normal and overweight individuals [27]. The difficulties for obese individuals in performing vertical and anteroposterior movements are well documented [2]. However, few studies have examined lateral movement in obese individuals, let alone the effect that weight loss could have on the task. Our results demonstrated that it is 1 of the tasks most sensitive to change, because improvements in this test occurred quickly, with a mean improvement of >50% at 12 months.

It is interesting that the maximal isometric knee torque was significantly lower at 6 and 12 months compared with baseline when expressed on an absolute basis. These findings are consistent with others that have demonstrated a reduction in parameters related to muscle adaptation of weight loss, such as metabolic rate and absolute muscle strength in both upper and lower extremities [28,29]. In that measures of strength and energy metabolism are best predicted from absolute levels of fat free mass in an obese population [30], it is not surprising that we observed a decrease in absolute strength after surgery. To adjust for changes in weight, an analysis for muscle quality was also done by expressing the maximal torque relative to body weight. We found an improvement in muscle quality at the final 2 points compared with the baseline measures, substantiating our earlier work in older adults undergoing a dietary restriction and exercise weight loss program [31]. However, others have failed to show that an adjustment for fat free mass corrects or compensates for changes in energy metabolism [29] because the resting energy expenditure was still less than the preweight loss levels expressed per unit of fat free mass.

Investigations of physical activity interventions after weight loss surgery procedures are extremely limited and are essentially nonexistent for strength and physical function measures. Thus, it is important to examine the effect of a formal exercise training program in this population to possibly preserve the quantity and improve the quality of lean body mass as measured by strength, energy metabolism, and clinical variables such as insulin resistance. An exercise program incorporating resistance training could enhance the measures of strength and provide greater improvements in function.

Because function and weight and body composition parameters improved during the study period, with the most weight lost and best function occurring at 12 months of postoperative testing, it was anticipated that a correlation would be found between the changes in these variables during the follow-up period. However, no significant associations were observed among the 12-month changes in these measures, whether expressed as absolute or relative changes. Additionally, no correlations were found between the changes in strength, function, or weight. This is in contrast to earlier cross-sectional studies that showed weight parameters were associated with physical function [6]. This relationship is frequently observed as a U-shaped curve, with both the higher and lower ranges of BMI associated with poorer function [3–5]. In behavioral intervention trials, levels of weight loss have been associated with improvements in function [8,9,32,33]. Thus, it was surprising that our data did not substantiate these findings. This discrepancy can be explained in that participants were fairly homogeneous with regard to their function and level of weight loss. In addition, the small sample size might have limited the correlations from achieving statistical significance.

The potential mechanisms underlying the changes in function after RYGB include changes in joint loads, alterations in regional body fat distribution, and reductions in inflammation [34–38]. These have all been shown to be related to functional impairments in other populations. These factors were not determined in the present study but are important to understand to optimize the benefits observed from the surgery.

This study was limited in that a control group was not used to adjust for the learning effect of the performance tasks. At baseline, the tasks performed were novel to the individuals and might have their limited performance. However, by the fifth measurement period, the individuals were more familiar with them. Providing several practice trials at each point served to reduce this learning effect. Additionally, the sample size was small, and >90% of the participants were women. Future studies should incorporate a control group, have a longer follow-up period, and examine the effect of structured exercise programs on strength, body composition, and function.

Conclusion

The results of the present study suggest that the massive weight loss that accompanies gastric bypass surgery provides significant improvements in physical function measures in as few as 3 weeks postoperatively for some performance tasks and by 3 months for all tests. These improvements result from the significant decreases in fat free mass and improvement in muscle quality.