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Original Research

Effect of Whey Protein in Conjunction With a Caloric-Restricted Diet and Resistance Training

Dudgeon, Wesley D.; Kelley, Elizabeth P.; Scheett, Timothy P.

Author Information
Journal of Strength and Conditioning Research: May 2017 - Volume 31 - Issue 5 - p 1353-1361
doi: 10.1519/JSC.0000000000001196
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Abstract

Introduction

Lean tissue mass is an important determinant for performance in athletes and a predictor of health in recreationally active adults (8,9,18). Individuals attempting to gain or maintain lean body mass (LBM) while concurrently losing fat mass (FM) often use a caloric-restricted or “cut diet.” Cut diets are typically 6 to 12-week protocols in which caloric intake is decreased and energy expenditure is increased in an attempt to reduce body FM. The type of exercise training performed and the magnitude of the energy deficit influence the tissue lost during the course of the diet, where greater deficits yield a greater body mass loss. Volek et al. reported that a hypocaloric (very low carbohydrate) diet may result in a preferential loss of total and regional FM when compared with a hypocaloric low-fat diet (18,19). Caloric-restricted diets are often used by athletes participating in aesthetic sports, such as dance, diving, gymnastics, and bodybuilding, or in weight class sports, such as wrestling, boxing, and martial arts. Nonathletes and recreationally active adults tend to emphasize the importance of reduced weight for general health and fitness, as data routinely show that lowered body fat and body mass index are associated with better health outcomes (9,12).

One of the primary concerns that both athletes and nonathletes face during weight loss interventions is maintaining or increasing lean mass, while decreasing FM. Oftentimes, individuals partaking in a caloric-restricted diet, in addition to a vigorous resistance training regimen, risk creating a negative protein balance, where the rate of protein catabolism exceeds the rate of protein synthesis (6,23). This may lead to muscle degradation, reduced muscle adaptations, performance, function, and recovery if left uncorrected. The expedient ingestion of nutrients after the cessation of exercise is required to help ensure the transition of net muscle protein balance from negative to positive (23). Protein supplementation increases muscle protein synthesis without a corresponding increase in protein degradation, which results in net-positive protein balance, allowing for maximal recovery, hypertrophy, and strength gains (6). Therefore, in addition to fat loss, muscle maintenance is of primary concern throughout the duration of the cut diet and requires adequate dietary protein consumption in both athletes and nonathletes (22). Increased consumption of dietary protein during weight loss interventions promotes a greater loss of FM and retention of muscle mass, the latter of which directly contributes to elevated resting metabolic rate (RMR) (8).

There is a wide range of protein products available for consumers with most claiming to provide enhanced body composition and lean muscle mass. An increasingly popular supplement is whey protein (WHEY), a high-quality complete protein with a high proportion of essential amino acids and branched-chain amino acids (e.g., leucine, isoleucine, and valine) that results in a more pronounced increase in muscle protein synthesis in response to exercise (3,4,20). However, what is not fully understood is the impact of WHEY supplementation in conjunction with a caloric-restricted diet. The results of this study could have an impact on the supplementation protocol for athletes who need to meet specific weight guidelines (e.g., wrestlers, mixed martial artists, boxers, etc.) and physique athletes. Therefore, the purpose of this study was to determine the effectiveness of a WHEY supplement on body composition, metabolism, and muscular fitness in young adult males using a cut diet while maintaining regular participation in resistance training.

Methods

Experimental Approach to the Problem

In a single-blind, matched group design, resistance-trained males participated in a 4 d·wk−1 body building style split resistance training program for 8 weeks in conjunction with the pre-exercise and postexercise ingestion of a WHEY nutritional supplement (Scivation Whey; Sciavation, Inc., Burlington, NC, USA) or carbohydrate-based nutritional supplement (POWERADE). In addition, all subjects were provided with a custom-designed caloric-restricted diet specifically based on each subject's individual pretraining body composition. Subjects were instructed that they must follow the diet provided to them for the entire program. Body composition and muscular performance were assessed before and after the 8-week progressive resistance training intervention period. This design allowed for the determination of the effectiveness of the cut diet in reducing mass across subjects, while also testing whether the WHEY supplement differed from the control treatment regarding body composition and muscle performance.

Subjects

Sixteen apparently healthy, resistance-trained (regular, consistent resistance training for at least 2 years before the onset of the study, and currently engaging in whole-body resistance training) males between the ages of 21–28 years volunteered to participate in the study. Subjects were excluded if they had less than 2 years of previous resistance training experience, lower-extremity or upper-extremity surgery within the past year, recent musculoskeletal injury, epilepsy, or another medical condition that would be exacerbated by the consumption of protein (i.e., excessive consumption of alcohol, diabetes, Lou Gehrig's disease, or branched-chain ketoacidura). All participants completed a confidential Physical Activity Readiness Questionnaire (Par-Q) to ensure that the current health status and physical activity habits for participation in this research was met. Before any data collection, all eligible subjects were made aware of the potential risks and benefits of the study, and signed university-approved written informed consent documents. The Institutional Review Board of the College of Charleston granted approval of all study procedures.

Procedures

Body composition and muscular performance testing sessions were performed for all subjects before the first dose of supplement and initiation of resistance training and diet program, and within 3 days after the conclusion of the 8-week intervention/training period. Every attempt was made to schedule pretesting and posttesting at the same time of day to avoid variability due to time. Subjects visited the Human Performance Laboratory in the Silcox Center at the College of Charleston for approximately 2 hours each visit to complete all testing procedures in the same order and were observed by the same research assistants.

Body Composition Assessment

Total body mass was measured on a digital medical scale (Tanita, Tokyo, Japan), and height was measured using a standard medical stadiometer (Seca, Chino, CA, USA). Percent body fat, FM, and fat-free mass were determined using hydrostatic weighing. Subjects were asked to enter the tank and remove any air bubbles that appeared in or on their clothes, hair, and/or skin. Subjects were then instructed to sit in the submerged chair that was attached to the load sensor. After the subjects were totally submerged and had exhaled as much air as possible from their lungs, a mass reading was recorded. This was repeated until 2 measures were within 100 g. Body volume was determined using Archimedes' principle, accounting for estimated lung volumes, and body density was determined (body mass/body volume) and entered the Siri equation for the estimation of FM and fat-free mass (2).

Muscle Performance

Upper-body and lower-body muscular strength was determined using the National Strength and Conditioning Association (NSCA) (14) protocol for a one repetition maximum (1RM). Each subject performed a 1RM bench press to measure upper-body muscular strength, and a 1RM parallel back squat to measure lower-body muscular strength. To assess local muscular endurance, 80% of the subject's 1RM on each lift was used for load, and subjects were instructed to complete as many repetitions as possible while retaining proper form. Trained research assistants spotted and supervised all lifts.

Resting Metabolic Rate

Resting metabolic rate was assessed before and after the 8-week intervention period using a ParvoMedics TrueOne metabolic cart after a 45-minute resting period in which participants were instructed to remain as quiet and motionless as possible in a dimly lit room. Participants were instructed to freely inhale and exhale throughout the test. Oxygen uptake was measured from expired air and required the use of a plastic canopy, preventing the need for a facemask or mouthpiece, which may artificially elevate RMR. Research assistants remained in the room to ensure that participants did not fall asleep.

Caloric-Restricted Diet

All subjects were provided with an individualized caloric-restricted diet based on individual data (body mass, body composition, RMR, etc.). Diets were designed by an industry consultant with previous experience consulting with physique athletes during precontest preparation. The caloric-restricted diet was designed as an 8-week cut diet for reducing body fat and used a modified carbohydrate-restricted diet approach (percent of total calories for workout days were 30% carbohydrates, 35% protein, and 35% fat; for off days were 25% carbohydrates, 40% protein, and 35% fat). Each individual's daily caloric and macronutrient intake was determined using the Harris Benedict formula with an activity factor of 1.35 (lightly active individual engaging in light exercise 1–3 d·wk−1) for workout days and 1.125 (sedentary individual) for off days. Subjects were given a diet card (Figure 1) for work out days and off days that listed the total caloric goal with 3 meal options per meal to attain the desired intake. The dietary intake needs were recalculated after 4 weeks of the study to account for any changes in body mass. Subjects were required to maintain the diet provided for them for the entire 8-week study period, and weekly interviews with subjects were incorporated to help achieve compliance.

Figure 1.
Figure 1.:
Sample diet card provided for subject. Each individual's daily caloric and macronutrient intake was determined using the Harris Benedict formula with an activity factor of 1.35 (lightly active individual engaging in light exercise 1–3 d·wk−1) for workout days and 1.125 (sedentary individual) for off days.

Supplementation Protocol

In a single-blind design, each participant was randomly assigned an 8-week supplementation protocol in one of 2 groups. Participants assigned to the protein supplement group consumed 28 g of a WHEY nutritional supplement (Scivation Whey, Scivation, Inc.) before and after each workout for a total of 56 g. Subjects in the control group ingested 28 g of a carbohydrate-based nutritional supplement (POWERADE) before and after each workout, for a total of 56 g per workout. Each subject was given a 4-week supply of their supplement with specific instructions on how to mix and when to consume. Subjects returned to the lab every 4 weeks to receive additional supplement. Subjects had to agree to refrain from consuming any other nutritional supplements during the study period.

Resistance Training Protocol

Participants engaged in a supervised progressive bodybuilding split style resistance training program consisting of 60–90 minutes of training 4 days per week for 8 weeks (day 1: chest/triceps, day 2: legs, day 3: shoulders, and day 4: back/biceps). Although the body parts trained remained consistent throughout the 8 weeks, the specific exercises used for each body part alternated and repeated every other week. Subjects performed 3–4 sets per exercise with 2-minute rest periods. During weeks 1 and 2, subjects completed 4–5 reps per set, and every 2 subsequent weeks, 2 reps were added per set resulting in subjects performing 10–11 reps per set during weeks 7 and 8. Subjects were provided and instructed to maintain their training log throughout the 8-week training period and returned to the laboratory every 4 weeks to have their individual training logs reviewed. Subjects (both treatment and control) not progressing through their program or complying with the stated nutrition and supplement requirements were dismissed from the study.

Statistical Analyses

Data are expressed as mean ± SE. To determine whether the WHEY provided an additive benefit to the caloric-restricted diet and resistance training program, data were analyzed (SigmaSat 3.5) using a priori paired and unpaired t-tests to assess changes over time and between group mean values, respectively. Tukey's Test was used for post hoc analysis. Intraclass correlation coefficients (ICCs) were performed to examine the test-retest reliability of the performance tests. The significance level was set at α = 0.05.

Results

Body Composition

There were no differences in body mass change between the WHEY and carbohydrate (CON) groups; however, both groups lost body mass (2.4 ± 0.7 kg; p ≤ 0.05) during the trial period, suggesting the calorie restricted diet was successful (Figure 2). The WHEY group maintained LBM during the trial, whereas the CON group had a 1.4 ± 0.1% (pre: 67.8 ± 2.5 kg vs. post: 66.9 ± 2.5 kg) loss in LBM (p ≤ 0.05) (Figure 3). Finally, the WHEY group lost 20.9 ± 3.3% (11.9 ± 2.1 kg vs. 9.4 ± 1.6 kg) FM (p ≤ 0.05), and while the CON group nonsignificantly lost 1.4 ± 0.7 kg FM (p > 0.05), the difference in FM lost between groups poststudy was not different (p = 0.20) (Figures 4–6).

Figure 2.
Figure 2.:
Change in body mass between WHEY and control groups after 8 weeks study period. #Different from pre within group, p ≤ 0.05.
Figure 3.
Figure 3.:
Change in lean body mass (LBM) between WHEY and control groups after 8-week study period. *Different from comparison group, p ≤ 0.05; #different from pre within group, p ≤ 0.05.
Figure 4.
Figure 4.:
Change in LBM of WHEY and control groups after 8-week study period.
Figure 5.
Figure 5.:
Change in fat mass (FM) between WHEY and control groups after 8-week study period. *Different from comparison group, p ≤ 0.05; #different from pre within group, p ≤ 0.05.
Figure 6.
Figure 6.:
Change in FM of WHEY and control groups after 8-week study period.

Metabolism

Resting metabolic rate, in terms of calories burned per minute, decreased in the WHEY group (p ≤ 0.05) but not in the CON group (p > 0.05), although the difference in changes between the groups was not significant (p = 0.19). Not surprisingly, this trend held when translating these data to a 24-hour period (WHEY: 2,002 ± 101 vs. 1,286 ± 34 kcals·d−1; CON: 1,898 ± 261 vs. 1,586 ± 49 kcals·d−1).

Muscular Strength and Local Muscular Endurance

Both muscular strength and local muscular endurance were measured for the lower body (squat) and upper body (bench press). There was no difference (p = 0.22) in lower-body strength changes after the study between the groups, as both the WHEY (pre: 133 ± 5 vs. post: 144 ± 3 kg; p ≤ 0.05) and CON (pre: 124 ± 10 vs. post: 128 ± 12 kg; p ≤ 0.05) groups showed significant improvements. Upper-body tests showed a different result, as there was a difference in how the groups responded (p ≤ 0.05), with the WHEY group increasing strength (pre: 103 ± 3 vs. post: 107 ± 4 kg; p ≤ 0.05) whereas the CON did not change (pre: 101 ± 3 vs. post: 97 ± 2 kg; p > 0.05) (Figure 7). Both groups increased squat repetitions (p ≤ 0.05) compared with pre (WHEY: 12 ± 2 vs. 15 ± 2 reps; CON: 14 ± 1 vs. 19 ± 1 reps), and the increase was greater in the CON group (p ≤ 0.05). Differences were found with upper-body muscular endurance, with the CON group having a greater increase in repetitions (WHEY: 9 ± 0.3 vs. 9 ± 0.3 reps; CON: 7 ± 1 vs. 9 ± 0.2 reps; p ≤ 0.05). ICCs for the lower-body 1RM squat test was R = 0.999, 80% 1RM squat test for reps was R = 0.991, upper-body 1RM bench press test was R = 0.684, and 80% 1RM bench press test for reps was R = 0.756 (Figure 8).

Figure 7.
Figure 7.:
Change in upper-body and lower-body strength between WHEY and control groups after 8-week study period. *Different from comparison group, p ≤ 0.05; #different from pre within group, p ≤ 0.05.
Figure 8.
Figure 8.:
Change in upper-body and lower-body strength between WHEY and control groups after 8-week study period. *Different from comparison group, p ≤ 0.05; #different from pre within group, p ≤ 0.05.

Discussion

The aim of this study was to determine the effectiveness of a WHEY supplement in conjunction with a hypocaloric diet, on body composition, RMR, and muscular fitness in healthy resistance-trained males. Previous reports suggest maintaining muscle mass while reducing FM is difficult; yet we hypothesized that the WHEY supplement would elicit an effect on muscle recovery from exercise and maintain muscle mass and muscular fitness (5,18,21).

Both WHEY and CON groups engaged in identical, supervised resistance training programs and received individualized hypocaloric diets for 8 weeks; therefore, changes in body composition and muscular fitness are most likely the result of the protein supplement, compared with the ingestion of the carbohydrate placebo supplement. This is an important discovery because protein supplements such as WHEY are often relied on to maintain or improve muscle mass, to aid muscle recovery, to enhance athletic performance, and to reduce the risk of sarcopenia, especially in older adults (5,15,18).

Both WHEY and CON groups reduced overall body mass after the 8-week intervention, attesting to the effectiveness of the hypocaloric diet. However, the WHEY group experienced a decrease in FM that was significantly different from pretrial values, and from the CON group, indicating that the WHEY supplement was more effective than the carbohydrate supplement at promoting fat loss. This finding is consistent with previous studies that demonstrated a decrease in overall body mass and FM when comparing the consumption of a WHEY supplement with a carbohydrate supplement within a group of healthy, resistance-trained men (3). It is possible that the CON group did not lose FM because carbohydrate supplementation stimulated a greater insulin release, which is not as effective as protein supplements in stimulating muscle anabolic pathways (7).

We anticipated an increase in lean muscle mass after the conclusion of the resistance training and WHEY supplementation period; however, only the WHEY group maintained LBM (0 ± 0.8 kg), whereas the CON group decreased LBM (0.9 ± 0.1 kg). It is possible that the decrease in lean mass can be attributed to decreased myofibrillar synthesis in the CON group, potentially a result of a lower consumption of dietary protein, combined with a muscle-damaging resistance training program. Hector et al. (8) found that WHEY supplementation postexercise attenuated the decline in postprandial rates of myofibrillar protein synthesis after weight loss, which was important in preserving lean mass during weight loss interventions. Similarly, Joy et al. (9) found that a WHEY supplement, in addition to a resistance training program, in resistance-trained males was effective in optimizing muscle protein accretion and muscle fitness. Furthermore, it is also possible that the WHEY decreased muscle protein degradation by providing enough available amino acids that the body did not have to break muscle down to provide the necessary amino acids (16). Thus, the lack of a WHEY supplement may have allowed the postexercise decline in myofibrillar protein synthesis in the CON group.

Previous studies using WHEY supplements have demonstrated that protein supplementation is more effective than carbohydrate supplementation at maintaining LBM and improving overall body composition (3,4,13,22). Willoughby et al. (22) found that a combined protein supplement (whey and casein) was effective in improving muscle mass and strength, and improving overall body composition. Similarly, Candow et al. found that a thrice-daily consumption of a WHEY supplement in healthy, young males and females was effective in increasing lean tissue mass and improving body composition (4).

Protein quality is also an important determinant of LBM responses to resistance training (20). Numerous researchers have demonstrated the ergogenic effects of WHEY on lean muscle mass in both untrained and trained individuals. Candow et al. illustrated that WHEY supplementation increased the ratio of protein synthesis to degradation postexercise in young untrained males and females. In a study conducted on healthy young resistance-trained males, a whey nutritional intervention increased protein accretion and lean muscle mass while also improving muscle function (4). Furthermore, researchers have found that daily supplementation of soy lowered circulating testosterone levels, whereas whey supplementation blunted cortisol response postexercise. Therefore, whey may provide a more anabolic environment than soy because of its rapid rate of absorption and ability to blunt the cortisol response postexercise (10).

The preservation of or increase in lean mass continues to be an important research topic, especially for athletes trying to improve body composition while maintaining performance and for older adults who risk obesity or age onset sarcopenia and other age-related diseases (5). Providing these persons with adequate and high-quality protein, such as WHEY, can stimulate myofibrillar protein synthesis, influence anabolic hormones, and in turn preserve LBM (5,18). Our data suggest that WHEY supplementation in individuals attempting to lose weight through caloric restriction can achieve maintenance of lean tissue mass while experiencing a loss of FM.

Eight weeks of resistance training combined with a WHEY supplement did not elicit a significant increase in RMR. Interestingly, the WHEY group decreased RMR compared with baseline values, whereas the CON group maintained RMR over the same time span. Variation in RMR is largely determined by muscle mass, where increases in muscle mass increase RMR because the muscle consumes a greater amount of energy at rest, compared with fat tissue (7). The CON group demonstrated a decrease in lean mass without a concurrent decrease in RMR, possibly because they only decreased their lean mass by 0.9 kg, which is only 0.5% of total mass (mean = 179.1 kg). Therefore, the decreased lean mass would not contribute to the change in RMR to a significant degree.

Other researchers have shown that protein supplementation in conjunction with resistance training is effective in increasing RMR above baseline values. Hambre et al. (7) demonstrated that after a 12-week resistance training and protein supplementation (33 g WHEY per day) program in healthy males, both RMR and lean tissue mass were increased similarly. However, the use of a hypocaloric diet in our study makes our findings unique and can partially explain the lack of observed changes in RMR.

There is a growing research interest into the anabolic benefits of protein supplements compared with a carbohydrate supplement during resistance training. Willoughby et al. (22) indicated that whey/amino acid supplementation resulted in greater increases in upper-body (bench press) and lower-body (leg press) strength, when compared with a carbohydrate supplement. However, both of the aforementioned studies used multiple-ingredient protein supplements and caloric neutral diets, whereas this study used a WHEY supplement in conjunction with a hypocaloric diet. After an 8-week period, the WHEY group showed small improvements in both upper-body and lower-body strength, whereas the CON group only showed improvements in lower-body strength. Interestingly, the strength values in the WHEY group were not significantly greater than the values from the CON group in lower-body strength, despite the change in the WHEY group being twice that of the CON group.

These results may be attributed to the specific effect of WHEY on muscle fibers. Ingestion of WHEY and its constituent amino acids stimulates anabolic hormone release and promotes the synthesis of muscle fibers, especially type II muscle fibers, which enables powerful movements that promote strength rather than endurance outcomes (2,18). It should be noted that placebo groups were consuming protein in their diets, so they too would be able to promote muscle fiber hypertrophy, although to a lesser extent. Furthermore, these subjects were already experienced in weight training, so the type of training (this was not assessed as inclusion criteria) they were accustomed to could explain the presence or absence of strength/endurance changes.

Other studies have demonstrated that a combination of whey with other protein supplements, such as casein and free amino acids (i.e., leucine), is more effective than an isolated WHEY supplement or an isocaloric carbohydrate supplement in promoting muscle anabolism and muscle strength, although with inconsistent results (2,3,11,17,18). A study by Cornish et al. illustrated the muscular strength benefits of a conjugated linoleic acid/creatine/whey (CCP) protein supplement when compared with creatine/placebo (CP) and whey/placebo (P) supplement groups. Increases in bench press strength, leg press strength, and lean tissue mass were greater in the combined group (CCP) than the isolated creatine (CP) or whey (P) groups (6). Burke et al. (3) compared a WHEY/creatine monohydrate supplement against an isolated WHEY supplement and reported that the subjects who consumed the WHEY/creatine supplement experienced greater increases in lean tissue mass and muscular strength than the WHEY or placebo group. Andersen et al. (1) illustrated that the ingestion of a protein supplement blend (whey, casein, egg white, and glutamine) 1 hour before and after exercise combined with a 14-week resistance program was more effective than an isocaloric carbohydrate in improving muscle performance as tested by a vertical jump.

Some researchers contend that a WHEY supplement combined with amino acids elicits the greatest beneficial effects on muscle protein synthesis and strength. Verreijen et al. (18) found that a supplement with high WHEY, leucine, and vitamin D-enriched content preserved muscle mass during intentional weight loss (defined as training in addition to a hypocaloric diet) in obese older adults. However, in contrast to the aforementioned study conducted by Verreijen et al., Mielke et al. (12) compared muscular strength benefits from a WHEY/leucine supplement against a carbohydrate placebo and nonsupplement group, and found that the gains in muscular strength were equivalent between the carbohydrate and the WHEY/leucine groups. Similarly, Spillane et al. found that the periexercise ingestion of a multi-ingredient protein nutritional supplement (39 g maltodextrin, 7 g whey, and 4 g creatine monohydrate) was not effective in preferentially improving body composition, muscle performance, or muscle protein synthesis (17).

The variability in experimental factors such as the quantity of the supplements, the type of supplements, the timing of ingestion, training status, intensity of training, and external dietary intake (isocaloric, hypercaloric, or hypocaloric) make direct comparisons of these studies difficult (12). In this study, an isolated WHEY supplement promoted a greater loss in FM and preservation of LBM and (lower body) muscular strength than a carbohydrate placebo after 8 weeks of heavy resistance training and a reduced calorie diet. Although it is not novel that a protein supplement can be more effective than a carbohydrate supplement at maintaining muscle mass and performance, what is unique is realizing these changes during a reduced calorie diet.

Practical Applications

The data from this study can be directly implemented by sports performance coaches, athletic trainers, sport coaches, fitness trainers, athletes, and active adults who engage in resistance training and are concerned with body composition. Many times, athletes are asked to lose body mass in an attempt to improve performance, but this often leads to a loss of muscle mass and hence poorer performance. The results of this study indicate that an 8-week progressive strength training program performed in conjunction with a hypocaloric diet and a WHEY supplement can maintain LBM while promoting loss of FM. Although applicable to many athletes, this information may be especially valuable to wrestlers, boxers, mixed martial artists, and physique athletes (i.e., bodybuilders, fitness competitors, etc.) who need to maintain lean mass and performance while still “making weight.”

Acknowledgments

The authors would first like to thank the subjects for their participation. Intense resistance training while on caloric restriction is not easy, and we appreciate their efforts in this process. The authors would also like to thank Chuck Rudolf, RD. for designing the diets. The authors would like to thank Sciavation Inc. for providing product and funding for this research. The results of the study do not constitute endorsement by the authors of the National Strength and Conditioning Association.

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Keywords:

“cut” diet; muscular performance; body composition

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