JSCR (2003) HMB and Resistance Exercise

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Journal of Strength and Conditioning Research, 2003, 17(1), 34–39 2003 National Strength & Conditioning Association

The Effect of -Hydroxy -Methylbutyrate onMuscular Strength and Body Composition in

Collegiate Football Players JACK RANSONE ,1 KERRI NEIGHBORS ,2 ROBERT LEFAVI ,3 AND

JOSEPH CHROMIAK4

1College of Education, Oklahoma State University, Stillwater, Oklahoma 74078; 2Oklahoma Dietetics Association,Stillwater, Oklahoma 74078; 3College of Health Professions, Armstrong Atlantic State University, Savannah,Georgia 31419; 4College of Education, Mississippi State University, Starksville, Mississippi 39762.

ABSTRACT

This study assesses the effects of daily -hydroxy -meth-ylbutyrate (HMB) supplementation on muscular strength(bench press, squats, and power cleans) and body composi-tion (body weight and body fat) among collegiate footballplayers undergoing a strenuous exercise program. Subjectswere collegiate football players (n 35) training under thesupervision of certified strength coaches averaging 20 hoursof weekly exercise. In the first supplementation period, 16 of the 35 subjects were supplemented with 3 g of HMB per dayfor 4 weeks; the other 19 received a placebo followed by a1-week washout period and then a second supplementationperiod in a randomized double-blind crossover, placebo de-sign. There were no significant changes ( p 0.05) in mus-

cular strength, including bench press, squats, and powercleans, among the subjects. There were also no significantchanges ( p 0.05) in body composition, including body fatand body weight. Very little clinical evidence exists for sup-plementing HMB in athletic populations.

Key Words: athlete, ergogenic aid, exercise, HMB, pro-tein

Reference Data: Ransone, J., K. Neighbors, R. LeFavi,and J. Chromiak. The effect of -hydroxy -methyl-

butyrate on muscular strength and body compositionin collegiate football players. J. Strength Cond. Res.17(1):34–39. 2003.

Introduction

Athletes are constantly searching for means of im-proving performance through dietary supple-

ments that promise performance enhancing or ergo-genic benefits. The most common dietary supplementsin the market include creatine monohydrate, -hy-droxy -methylbutyrate (HMB), antioxidant vitamins,amino acids, caffeine, and protein powder (1, 7, 8, 12,19, 33). Sales of supplements, bars and beverages for-

mulated to enhance athletic performance and recoveryreached $1.26 billion in 1997 and are expected to in-crease (29). In the last few years, HMB, a byproductof the essential amino acid leucine, has become one of the best-selling sports supplements (5). Because it isfound in both plant and animal foods, including cat-fish and grapefruit, and is a metabolite of an aminoacid, HMB has been classified as a dietary supplement(7, 11, 19, 36). It has been estimated that a 70-kg hu-man would produce from 0.2 to 0.4 g HMB each day,depending on dietary leucine intake (28).

The proposed effects of HMB supplementation arenumerous (14, 17, 24, 28). It has been hypothesized

that HMB supplementation reduces the catabolic ef-fects of resistance training (27, 28, 32). Recent inves-tigations have shown that rigorously trained HMB-supplemented subjects significantly gain morestrength and lean body mass than unsupplementedsubjects (27, 28, 38). It has been suggested that HMBmay reduce low-density lipoprotein cholesterol (24),

but not all studies have shown alterations in blood lip-id concentrations with HMB supplementation (10). Todate, no adverse effects have been seen in animals orhumans supplemented with HMB (6, 10, 24, 26, 38).

The effect of HMB supplementation on strengthand body composition in individuals undergoing rig-

orous resistance training has been tested (9, 34). In oneinvestigation, body fat significantly decreased and lean

body mass increased in the HMB-supplemented subjects (27). The development of fat-free mass was re-flected in a 55% greater gain in the bench press lift.The effect of HMB on body fat has been validated ina few animal and human studies (4, 25, 27, 37). HMBtreatment increases beta-oxidation of palmitate by30%, decreased lactate dehydrogenase (LDH) by 25%,and increased cellular expression of creatine kinase by25%. These data suggest that HMB exerts several ef-



HMB Supplementation 35

Table 1. Demographic data.*

Age (y) Height (in.) Weight (kg) Body fat (%)

X 21.3 1.2range 19.2–23.6

72.1 0.2range 69.0–75.0

97.6 18.8range 74.1–138.6

12.4 7.0range 3.8–28.5

* All values are at pretest.

fects on muscle cells, potentially increasing the cell’soxidative capacity, stabilization of cell membrane, andenhancing the expression of muscle-specific proteins.Also, the increase in fatty acid oxidation may explainsome of the decrease in muscle fat proposed withHMB supplementation in humans.

The exact mechanism whereby HMB influencesmuscle metabolism is unknown; however, there aretwo hypotheses. HMB may act as a precursor to cel-lular muscle repair by stimulating proteinosis, whichwould increase collagen synthesis and connective tis-

sues (33, 37). The net effect of these actions would bea reduction in recovery time, which could potentiallyincrease strength and lessen the risk of overtraining.The other hypothesis suggests that HMB may regulateenzymes responsible for muscle tissue breakdown.There is evidence that HMB supplementation decreas-es biochemical markers of muscle breakdown amongstrength trainers and directly decreases the degrada-tion of muscle protein in vitro (2–4, 24, 27, 28, 30). Theobjective of this research was to conduct a randomizedcontrolled trial to evaluate the effects of daily HMBsupplementation on muscular strength and body com-position among collegiate football players undergoing

a strenuous exercise program.

MethodsExperimental Approach to the Problem

This study was experimental in nature and followed arandomized double blind crossover, placebo design.The subjects were assigned randomly to one of 2 ex-perimental groups. In the first supplementation peri-od, 16 of the 35 subjects were supplemented with 3 gof HMB per day for 4 weeks; the other 19 receivedplacebo. There was a 1-week washout period, and thesubjects received the other supplement for 4 weeks.

Subjects The subjects (n 35) were National Collegiate AthleticAssociation Division I football players at a major Mid-western university training under the supervision of certified strength coaches. All subjects (Table 1) had atleast 4 years of strength-training experience and ad-hered to the similar regimens of volume, averaging 20hours of weekly exercise.

Each subject gave written, informed consent to par-ticipate in these experiments after the purpose, pro-cedures, and known risks of the tests were explained

in accordance with the University Institutional ReviewBoard. Each subject completed a physical evaluationand medical history questionnaire designed to evalu-ate health status, medication, and previous injury sta-tus. Any indication of a possible health problem thatmight compromise the safety of subjects or the validityof the study excluded the individual from the presentinvestigation.

Exercise Training

Each subject participated in supervised exercise ses-sions (Table 2) approximately 4 hours per day for 4days each week throughout the 9-week experimentalperiod prior to the start of the competitive season. Awarm-up consisting of 10 minutes each of jogging andstretching preceded each practice session. Bothstrength and endurance exercises were performed eachday of practice. Strength exercises were performed at10 exercises per session, with 8–12 sets per exerciseand 2–10 repetitions per set. The endurance drills con-sisted of speed and tempo exercises; they were per-formed with 26–30 seconds recovery time betweenrepetitions and full recovery between sets.

Testing Procedures

The 9-week double blind, crossover design required 2stages of supplementation: (a) HMB and (b) placebo.One week lapsed between the end of the first 4-weektreatment period and the beginning of the second 4-week treatment period. A previous investigationshowed that HMB levels returned to basal levels bythe fourth day postsupplementation (17). Consequent-ly, each subject underwent both treatments with an in-tervening washout period of 7 days. Following thewashout period, subjects crossed over to the othertreatment and the protocol was repeated. All subjectsreported to the test site prior to initiating the treatmentschedules to complete a release of pertinent demo-graphic information.

During the first supplementation period, subjectswere asked to ingest either 750-mg capsules of HMBor placebo capsules containing an inert substance(methylcellulose) for 28 days. The subjects were in-structed to take 4 capsules a day: 2 with breakfast, 1with lunch, and 1 with dinner. The total intake of HMBwas 3 g per day. The rationale of taking the capsuleswith meals was to enhance compliance. The supple-ments were distributed at the beginning and 2 weeksinto each supplementation period. Therefore, 56 cap-



36 Ransone, Neighbors, LeFavi, and Chromiak

Table 2. Exercise program.*

Type of exercise Drill/lift Distance Recovery

Warm-up every session 10 min jogging10 min stretching

Endurance (speed) 2sessions/wk

Parachute 4 40 yards Full between sets, 26–30s between repetitions

Surgical tubing 4 50 yardsStadium steps 4 flightsBox jumps 2 20 sFoot ladder 4 20 yardsMedicine ball 2 10 yardsMetabolic training (position-specific

running patterns)6 50 yards

Endurance (tempo) 2sessions/wk

50-yard dash 2 5 Full between sets, 26–30s between repetitions

Metabolic training 6 50 yards

Strength 4 sessions/wk(70–90% RM†10 lifts/session)

Snatch pulls, power pulls, push press, splitsnatches, incline plyometric push-ups,step-ups, jump squats, seated power pass,

leg curls, squats, bench press, 2-way E-Zcurls, front squats, incline bench, uprightrow, step-ups, sumo deadlift, militarypress, let curls, 2-way latissimus pull-down, 2-way E-Z curls, triceps push-down, close grip, hang clean, up-rightrow, pullover press, dumbbell rows

8–12 sets

2–10 repetitions

Full between sets, 1–2min between repeti-tions

* Not all drills or lifts performed at each exercise session.† RM repetitions maximum.

sules were given 4 times: at the beginning and midwaythrough both supplementation periods. Constant ver-

bal reinforcement was given to ensure the subjects ad-hered to the protocol. All capsules were produced to

be identical by the nutritional supplement manufac-turer (Twin Laboratories Inc., Hauppauge, NY). Thesubjects were instructed not to alter their lifestyles ordietary practices during the investigation. In addition,they were asked to report whether there were any sideeffects.

Prior to supplementation and on the day followingeach 28-day supplementation period, subjects reportedto the testing site, having been instructed not to eatfor 3 hours prior to testing. In order to obtain the mostaccurate and maximal exercise effort, vigorous physi-cal activity was discouraged for 24 hours prior to thescheduled test appointment. Subjects were instructedto report to the testing site well hydrated and nour-ished, and a full night’s sleep was strongly recom-mended. A battery of tests involving muscularstrength and body composition was performed. Sub-

jects were tested in groups and competition wasstressed. A 10-minute warm-up and stretching periodpreceded each testing session. All strength tests used3–5 repetition maximum (RM) efforts allowing predic-tion of 1RM effort (22). Strength tests included the

bench press, power cleans, and squats, recorded to thenearest pound. Body composition was assessed using

body weight and the Jackson and Pollock (thigh, chest,and abdominal) equations to determine body densityfor healthy male athletes (15). For the dietary analysis,food frequency questionnaires were evaluated usingthe exchange lists for meal planning of American Di-abetes Association, Inc. and the American Dietetic As-sociation (35).

Statistical Analyses

Comparisons between the placebo and HMB treat-ments were made using a randomized split-plot fac-torial analysis of covariance to compare the mean dif-ferences between tests. Tukey post-hoc analyses were

performed to determine the differences betweenmeans using a level of significance set at 0.05. The re-peated factors were treatment in reference to HMB/placebo and order of testing. The covariates are max-imal strength values, body weight, and sum of bodyfat skinfolds.

Results

There were no differences for muscular strength (Table3), including bench press ( p 0.05), power cleans ( p 0.05), and squats ( p 0.05).




Table 3. Muscle strength values.

Mean(SD) F value p values

Bench pressPower cleansSquats

300 58.2298 52.5452 86.3

0.4020.8071.235

0.050.050.05

Table 4. Body composition results.

Weight (lb)

PretestHMB*

posttestPlaceboposttest

Body fat (%)

PretestHMB

posttestPlaceboposttest

215 215 216 12.4 11.5 12.2

* HMB -Hydroxy -methyl butyrate.

In addition, there were no significant differencesfor body composition (Table 4), body fat ( p 0.05), orweight ( p 0.05). The repeated factor of treatmentwith reference to HMB/placebo and order of testingwas not significant ( p 0.05). The food frequencyquestionnaire was evaluated using the exchange list formeal planning of American Diabetes Association, Inc.and the American Dietetic Association (34). Reportedmean caloric intake, based on analysis of food fre-quency questionnaires, was 2,600 cal, consisting of 43–45% carbohydrate, 21–23% protein, and 33–35% fat.The experimental period, which comprised the sum-mer months of June, July, and August, did not includea training table that would have allowed close moni-toring of the dietary intake.

Discussion

Daily supplementation of HMB in collegiate footballplayers undergoing a strenuous exercise program didnot alter muscular strength, total body weight or per-cent body fat. The exercise protocol followed in thisinvestigation is consistent with a previous investiga-tion (13), which determined that exercise 4–5 times perweek is an optimal choice in developing strength, en-durance, and muscle mass. Our study is consistentwith other studies showing no effect of HMB on bodyfat (9, 20). One study reported a greater decline in per-cent body fat with HMB supplementation with a p val-ue of 0.08 (31). Studies have reported greater increasesin fat-free mass following strength training in trainedand untrained male subjects (11), and in untrainedmale and female subjects (31). However, in one study,the greater increase in fat-free mass observed early inthe study was not maintained after 6 weeks, and sub-

jects in the HMB group received a nutrient beveragecontaining protein, whereas those in the placebo

group did not (28). In another study, the increase infat-free weight after 4 weeks of HMB supplementationwas 1.4 kg, compared with 0.9 kg in the placebogroup, and the p value was 0.08 (31). Other studieshave reported that HMB supplementation during 4weeks of resistance training does not alter body fat(20). The lack of effect of HMB on 1RM strength for

the bench press, squat, and power cleans in the currentstudy is consistent with other studies reporting no ef-fect on 1RM strength (10, 20). HMB supplementationto men and women during 4 weeks of resistance train-ing increased upper-body strength, but not lower-

body strength, compared with placebo (31). HMB in-creased peak isometric torque and peak isokinetictorque at several concentric and eccentric velocities,

but did not affect 1RM strength for several exercises(11). Another study reporting increased strength gainswith HMB supplementation did not measure 1RMstrength, but based this conclusion on greater work-load increases in the HMB group (28). Finally, an in-

crease in upper-body but not lower-body strength wasreported following 4 weeks of HMB supplementation(31).

Based on blood enzyme levels and urinary 3-meth-yhistidine excretion, it appears that HMB reducesmuscle damage and muscle protein degradation dur-ing the first few weeks of initiating training or increas-ing the workload (10, 28). An additional study report-ed that plasma creatine phosphokinase levels ‘‘tend-ed’’ to be lower with HMB supplementation after 4weeks of resistance training (31), and another studyfound no significant differences between placebo- andHMB-supplemented groups after 4 weeks of strength

training (20). HMB supplementation reduced the in-crease in serum creatine phosphokinase and lactate de-hydrogenase concentrations following a 20-km run(17). It appears that HMB may be most effective wheninitiating an exercise training program or increasingthe workload of a training program.

This subject population in this study represented agroup targeted by supplement companies due to theirtraining regimen and competitive nature (1, 7). Al-though no training table was available during the ex-perimental period, it was the assumption of the inves-tigators that these subjects are representative of a typ-ical collegiate athlete in terms of diet and exercise hab-its. In short-term recall situations, the food frequencyquestionnaire has the potential to underestimate en-ergy and nutrient intake (18). Other limitations of foodfrequency questionnaires include intake data beingcompromised when multiple foods are grouped with-in single listings, and they are dependent on the abilityof the subject to describe their diet (21). Athletes maytend to focus more on eating and body compositionthan nonathletes. Consequently, desire for weightchange and level of dietary consciousness may also se-verely bias reported food intake in food frequency



38 Ransone, Neighbors, LeFavi, and Chromiak

questionnaire (16). Previous research showed the subjects’ average total caloric need in this study was ap-proximately 4,310 cal per day. Depending on severalfactors, such as metabolic rate, activity level, and foot-

ball position, the total caloric needs range from 39.0to 45.7 cal·kg1·d1 (23). Therefore, the reported meanintake of total calories consumed (2,600 cal per day)

during this study is much lower than the football play-ers’ estimated needs. The breakdown of macronutri-ents (44% carbohydrate, 22% protein, and 34% fat)consumed by the football players in this study is fairlyconsistent with macronutrient ratios reported in theliterature (23). However, given the relatively low totalcaloric intake of these subjects and the macronutrient

breakdown, the subjects’ intake of carbohydrates mayhave been suboptimal.

The lack of strength gains in the current investi-gation suggests that subjects may have been over-trained. The volume of exercise in this study was high-er than most other HMB-supplementation studies. Al-

though HMB may be most effective when increasingtraining volume or intensity, the extremely high totaltraining load may have attenuated the potential effec-tiveness of HMB to reduce muscle damage or protein

breakdown.

Practical Applications

This study was designed to assess the effect of dailyHMB supplementation on muscular strength and

body composition among collegiate football playersundergoing a strenuous exercise program. Recogniz-ing that caution should be observed in generalizingfrom this study’s results, it was concluded that sup-plementation of HMB had no effect on muscularstrength or body composition during an intensivestrength and conditioning program on well-trainedcollegiate football players. Prior research suggests thatHMB may be most effective when initiating an exer-cise training program or increasing the workload of atraining program. Research has also demonstratedthat HMB may induce small increases in strength andfat-free mass by reducing muscle damage and protein

breakdown. However, the extremely high total trainingload in the current investigation may have attenuated

the potential effectiveness of HMB to reduce muscledamage or protein breakdown. Additional research isneeded before HMB can be recommended as an er-gogenic supplement to reduce muscle protein catabo-lism during training periods when volume and inten-sity are increased.

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Address correspondence to Dr. Jack Ransone,[email protected].

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JSCR (2003) HMB and Resistance Exercise