Journal of Strength and Conditioning Research, 2007, 21(2), 419–423
? 2007 National Strength & Conditioning Association
EFFECTS OF SIX WEEKS OF
?-HYDROXY-?-METHYLBUTYRATE (HMB) AND
HMB/CREATINE SUPPLEMENTATION ON STRENGTH,
POWER, AND ANTHROPOMETRY OF HIGHLY TRAINED
DONNA M. O’CONNOR1AND MELISSA J. CROWE2
1Faculty of Education, The University of Sydney, Sydney, Australia;2Institute of Sport and Exercise Science,
James Cook University, Townsville, Australia.
ABSTRACT. O’Connor, D.M., and M.J. Crowe. Effects of six
weeks of ?-hydroxy-?-methylbutyrate (HMB) and HMB/creatine
supplementation on strength, power, and anthropometry of
highly trained athletes. J. Strength Cond. Res. 21(2)419–423.
2007.—This study investigated the effects of 6 weeks of dietary
supplementation of ?-hydroxy-?-methylbutyrate (HMB) and
HMB combined with creatine monohydrate (HMBCr) on the
muscular strength and endurance, leg power, and anthropome-
try of elite male rugby league players. The subjects were divided
into a control group (n ? 8), a HMB group (n ? 11; 3 g·d?1) or
a HMBCr group (n ? 11; 12 g·d?1with 3 g HMB, 3 g Cr, 6 g
carbohydrates). Three repetition maximum lifts on bench press,
deadlifts, prone row, and shoulder press, maximum chin-up rep-
etitions, 10-second maximal cycle test, body mass, girths, and
sum of skinfolds were assessed pre- and postsupplementation.
Statistical analysis revealed no effect of HMB or HMBCr on any
parameter compared with presupplementation measures or the
control group. HMB and HMBCr were concluded to have no er-
gogenic effect on muscular strength and endurance, leg power,
or anthropometry when taken orally by highly trained male ath-
letes over 6 weeks.
KEY WORDS. HMBCr, supplements, training, ergogenic
mended daily dose (3 g·d?1) of HMB will not el-
evate the testosterone to epitestosterone ratio (28), and it
is not currently listed as a banned or restricted substance
by the International Olympic Committee. Several studies
have indicated that HMB supplementation will increase
strength and lean muscle mass (17–19, 22, 30), whereas
others contradict these claims (5, 13–15, 23, 25, 27). This
controversy is complicated further by the fact that much
of the HMB literature is available only in abstract form
(1, 5, 14, 17, 19, 23).
Past studies reporting positive effects of HMB on
strength and lean muscle mass in untrained individuals
have supplemented at doses of 1.5 or 3 g·d?1over periods
of 4–8 weeks in both male and female subjects (17–19,
30). However, similar doses of HMB supplemented over
8 weeks in young adult (6) and elderly (23) populations
had no effect on strength. Because HMB purportedly in-
creases muscle size and strength, it would be of interest
to assess the effects of this supplement in subjects who
regularly participate in a weight training program. Pre-
-hydroxy-?-methylbutyrate (HMB), a metabolite
of the amino acid leucine, is a popular nutritional
supplement, particularly with people seeking
gains in muscle size and strength. The recom-
vious studies investigating the effects of HMB supple-
mentation in both trained and untrained subjects have
reported significant increases in fat free mass (18, 19) and
increases in some, but not all, measurements of strength
(18, 19, 22). Because the untrained subjects showed sim-
ilar responses, it was suggested that initial training sta-
tus would not influence the subjects’ ability to derive ben-
eficial effects from HMB supplementation (19).
A number of studies have failed to support the hy-
pothesis that HMB significantly enhances strength or
body composition in experienced resistance trained ath-
letes (13, 15, 25, 27). These studies supplemented HMB
at doses of 3–6 g·d?1for periods between 4 and 6 weeks.
Thus, the effects of HMB in resistance trained athletes
needs to be resolved.
Another popular nutritional supplement often mar-
keted in combination with HMB is creatine monohydrate
(Cr). Numerous studies have indicated that Cr supple-
mentation increases muscle Cr content, improves sprint
ability, and enhances gains in strength, power and fat
free mass during training (see 11, 12). Few studies, how-
ever, exist that examine the combined supplementation
of Cr and HMB (HMBCr). One study reported that
HMBCr given to college footballers caused a significant
increase in fat free mass, but no difference in body fat
loss compared with placebo and HMB groups over 4
weeks of resistance training (14). Another study reported
significant strength improvement in the power clean but
not bench press or squat following HMBCr supplemen-
tation (1). Interestingly, HMB supplementation alone in
both these studies had no effect on strength or body com-
position (1, 14). Creatine, HMB, or HMBCr supplemen-
tation was examined in non–resistance trained subjects
(10). Lean body mass increased after Cr supplementation,
body fat increased after HMBCr supplementation, and
overall strength increased for all 3 supplement groups
compared with a placebo group (10). Thus, the reported
findings of HMBCr supplementation on strength and
body composition are equivocal and require further in-
Given the conflicting evidence available on the ergo-
genic effects of HMB and HMBCr, it is the aim of this
study to investigate the effects of these supplements on
the muscular strength and endurance, leg power, and an-
thropometry of professional athletes who have been in-
volved previously in a regular strength training program.
A supplementation period of 6 weeks was chosen to en-
420 O’CONNOR AND CROWE
?-hydroxy-?-methylbutyrate (HMB) groups.
Mean (SE) physical characteristics of the subjects in the control, ?-hydroxy-?-methylbutyrate/creatine (HMBCr) and
Body mass (kg)
able comparison of the findings with those of past studies
into HMB that utilized supplementation periods of 4–8
weeks. It is expected that this study will assist in clari-
fying the responses to HMB and HMBCr in trained sub-
Experimental Approach to the Problem
A repeated-measures design was employed where all sub-
jects were tested prior to and following the 6-week sup-
plementation period. A number of the professional ath-
letes declined to take any supplements for various rea-
sons and, therefore, were allocated to the control group
(n ? 8). For this reason, it was not possible to employ a
double-blind protocol. Although the control group was
self-selected, there were 3 forwards, 4 backs, and 1 player
who could play in any position in this group, indicating a
balanced representation of player positions. The remain-
ing subjects were assigned randomly to the HMB group
(n ? 11) or the HMBCr group (n ? 11) and, where pos-
sible, matched for body weight, V˙O2max (Table 1), and
player position. Therefore, the subjects in the HMB and
HMBCr groups were aware of the fact that they were
taking HMB, but were unaware of whether they con-
sumed HMB alone or in combination with Cr.
Thirty males from an Australian National Rugby League
team volunteered to participate in this study. The mean
age, weight, and V˙O2max of the subjects are outlined in
Table 1. The V˙O2max was determined as previously de-
scribed (21). The subjects were professional rugby league
players, having had at least 2 years experience playing
at a national or state level. All subjects had participated
in a regular strength training program for at least 4
years, and therefore were familiar with strength training
techniques. Subjects were asked to refrain from consum-
ing any nutritional supplements 1 month prior to testing
and to avoid any supplements other than those being
studied during the testing period.
Ethics approval for the project was granted from the
James Cook University Ethics Committee. The subjects
were given clear instructions on the procedure involved
before providing their written informed consent. This
study was part of a larger study that also investigated
the effects of HMB and HMBCr on aerobic and anaerobic
power (21) and indices of health (4).
A repeated measures design was employed where the
subjects underwent baseline testing followed by a 6-week
supplementation period at the end of which the baseline
tests were repeated. All subjects were familiar with the
testing protocols, having previously undergone these tests
on a minimum of 2 occasions as part of their regular fit-
ness assessment. Both testing sessions were performed
over a 5-day period during preseason training, with the
last testing session administered 1 week prior to the com-
mencement of the national competition. The tests per-
formed are outlined below.
Muscular Strength and Endurance Tests. Strength
was assessed by the 3 repetition maximum test (3RM) (2).
Four exercises were utilized using free weights: bench
press (intraclass correlation coefficient [ICC] ? 0.99),
deadlift (ICC ? 0.97), dumbbell shoulder press (ICC ?
0.99), and prone row (ICC ? 0.99). Upper body muscular
endurance was assessed with the maximum number of
chin-ups to exhaustion (ICC ? 0.98). The technical error
of measurement was ?3% for all tests.
Ten-Second Leg Power Test. A 10-second maximal cycle
ergometer test (26) was employed to assess leg power. The
subjects cycled at a slow to moderate pace for 3–5 minutes
to warm up before performing a maximal cycling effort
for 10 seconds. All subjects received verbal encourage-
ment throughout the duration of the test. Peak power
(W·kg?1) and total work (J·kg?1) were recorded upon com-
pletion of the test using a Repco Supermonitor (Repco Cy-
cle Co., Huntingdale, Australia). The ICC for test-retest
reliability for peak power and total work were both 0.99,
whereas the technical error of measurement was 7.3 and
Anthropometric Profile. Anthropometry was assessed
by body mass, skinfolds, girths, and bone diameters using
the procedures recommended by the International Society
for the Advancement of Kinanthropometry (20). The mea-
surements were conducted by a Level 3 kinanthropo-
metrist (technical error of measurement was ?3%). Body
mass was obtained using scales accurate to 50 g (UC-300
Precision Health Scales; A&D Co., Adelaide, Australia).
The 8 skinfold sites (triceps, subscapular, biceps, iliac
crest, iliospinale, abdominal, thigh, calf) were assessed
using Harpenden skinfold calipers (British Indicators,
West Sussex, UK). A metal tape measure (KDS Measure;
Kyoto Measuring Instruments Co., Kyoto, Japan) was
used to assess 6 girth measurements (arm relaxed and
flexed, chest, waist, hip, and midthigh). The 2 bone di-
ameters (humerus, femur) were assessed using a small,
sliding caliper (Mentone, Melbourne, Australia). All an-
thropometric measurements were the average of 2 test
values except where a greater than 10% discrepancy ex-
isted, in which case a third measurement was performed
and an average of all 3 measures were reported. All an-
thropometric measurements were made prior to any ex-
ercise and were assessed at the same time of day for each
subject at pre- and postsupplementation.
Supplementation Period. All subjects underwent the
same strength and conditioning program throughout the
6-week supplementation period. This minimized differ-
ences in training variables such as intensity, duration,
volume, and frequency. The training program consisted
of 8 sessions over a 5-day period, followed by 2 consecu-
tive rest days. Three total-body strength training sessions
and 1 speed/power session (45 minutes of speed drills,
plyometrics, resisted, and assisted training) were per-
formed each week. This was supplemented by 4 team con-
ditioning and skill sessions per week of approximately 90
HMB AND HMB/CREATINE SUPPLEMENTATION
and ?-hydroxy-?-methylbutyrate (HMB) supplemented groups at pre- and postsupplementation.
Mean (SE) muscular strength, endurance and leg power for the control, ?-hydroxy-?-methylbutyrate/creatine(HMBCr),
Bench press (kg)*‡
Shoulder press (kg)*‡
Prone row (kg)‡
10-second leg power?
Peak power (W·kg?1)*
Total work (J·kg?1)*
* p ? 0.05 significant main effect for time (pre- to postsupplementation).
† p ? 0.05 significantly higher than HMBCr and HMB at presupplementation.
‡ Control, n ? 8; HMB, n ? 11; HMBCr, n ? 11.
§ Control, n ? 6; HMB, n ? 9; HMBCr, n ? 6.
? Control, n ? 6; HMB, n ? 10; HMBCr, n ? 11.
methylbutyrate (HMB) groups at pre- and postsupplementation.
Mean (SE) body composition data for the control, ?-hydroxy-?-methylbutyrate/creatine (HMBCr), and ?-hydroxy-?-
Body mass (kg)†
Sum of skinfolds (mm)*†
Chest girth (cm)‡
Waist girth (cm)*‡
Hip girth (cm)*‡
Thigh girth (cm)‡
Femur diameter (cm)‡
Humerus diameter (cm) ‡
* p ? 0.05 significant main effect for time (pre- to postsupplementation).
† Control, n ? 7; HMB, n ? 11; HMBCr, n ? 11.
‡ Control, n ? 6; HMB, n ? 11; HMBCr, n ? 11.
minutes each, including a combination of agility drills,
aerobic, and anaerobic activities, plus skills training. All
training sessions were fully supervised and loads were
individually determined for each subject for every weight
session. Weight sessions were periodized for strength (2–
6 repetitions) and consisted of 25–30 sets per session at
an intensity of 80–95% 1RM. All the exercises used in the
3RM testing were incorporated in the training program.
The subjects had been participating in this resistance
program emphasizing hypertrophy for 8 weeks prior to
the testing period.
Because the subjects were not blinded as to groupings,
the control group (n ? 8) did not receive a placebo. The
HMB subjects received daily doses of HMB (3 g of the
calcium salt of HMB per day; Quality of Life Products,
Adelaide, Australia; n ? 11) or HMB/Cr (12 g·d?1of
HMBCr composed of 3 g calcium-HMB, 3 g Cr, and 6 g
carbohydrates; Quality of Life Products, Adelaide, Aus-
tralia; n ? 11). The subjects were instructed to dissolve
the HMB or HMBCr powder in 400 ml of 50% diluted
sports drink (4% carbohydrate, including 3% sucrose and
1% maltodextrin) and consume it in the morning within
3 hours of the morning training session. Control subjects
consumed only the diluted sports drink. Compliance with
taking the supplement was confirmed orally with all sub-
jects on each training day. To ensure that there were no
negative effects from taking the supplements, the sub-
jects were asked orally whether they suffered any side
effects as a result of taking the supplement.
All results were analyzed using a 2 (time) ? 3 (groups)
factorial analysis of variance with repeated measures on
the time factor. The analyses were performed with the
SPSS for Windows program (SPSS, Inc., Chicago, IL). The
alpha level was set at p ? 0.05. Statistical power is re-
ported for each significant finding. All data are presented
as mean (SE).
All parameters measured did not differ significantly be-
tween the 3 groups prior to supplementation (p ? 0.05;
Tables 1–3), with the exception of the control group,
which recorded significantly higher deadlift strength
compared with the HMB and HMBCr groups prior to sup-
plementation (p ? 0.002; power ? 0.94; Table 2).
All subjects participated in all assessments with the
exception of the deadlift, 10-second leg power test, and
anthropometry (Tables 2 and 3). The subjects who did not
participate in deadlifts or the leg power test excluded
themselves because of concern for reinjury after rehabil-
itation from a previous knee or back injury. The 2 sub-
jects missing from the anthropometry assessments failed
to attend the postsupplementation session.
422O’CONNOR AND CROWE
There were no significant differences in muscular
strength and endurance, leg power (Table 2), or anthro-
pometric parameters (Table 3) among the control, HMB,
and HMBCr groups as a result of the 6-week supplemen-
tation period (p ? 0.05).
There was a significant main effect for time (pre- vs.
postsupplementation), indicating a training effect for all
strength and power variables (p ? 0.05; power ranged
from 0.76–1.00) except 3RM prone row (p ? 0.05; Table
2). Sum of skinfolds (power ? 1.00), relaxed arm (power
? 0.63), waist (power ? 0.51), and hip (power ? 0.76)
girth also significantly decreased after the 6-week train-
ing program (p ? 0.05), with no difference among the 3
groups (p ? 0.05; Table 3).
Supplementation with either HMB or HMBCr did not
result in any adverse reactions or side effects.
The major finding of this study was that supplementation
with HMB or HMBCr for 6 weeks did not improve the
muscular strength and endurance, leg power, or anthro-
pometry of professional rugby league players undergoing
a resistance training program. This agrees with past
studies examining the effects of HMB on trained subjects
(5, 17, 19, 25, 27). However, our results disagree with
earlier studies (18, 19, 22) that utilized both trained and
The equivocal effects of HMB on strength and body
composition in past studies may be related to the training
background of the subjects. Untrained subjects may ob-
tain greater benefit from HMB supplementation than
trained subjects do. The subjects in the current study,
being well-trained professional footballers, had less po-
tential for strength development compared with un-
trained subjects. Repeated exposure to resistance train-
ing has been shown to suppress the breakdown of protein
and to result in less muscle damage and protein turnover
than experienced in an acute training period (24). Fur-
thermore, resistance training results in less myofibril
damage in trained as opposed to untrained subjects (7).
This reduction in muscle breakdown with chronic resis-
tance training may explain why the highly trained sub-
jects in the current study did not respond to HMB sup-
plementation in the same manner as reported in the lit-
erature for untrained or moderately trained individuals.
In support of this hypothesis, the mean strength on bench
press in the current study was similar to that reported
previously in trained athletes where HMB had no effect
(15) and is considerably higher than the bench press
strength of subjects who responded positively to HMB
(22). Therefore, the benefits to be gained from HMB sup-
plementation may be limited in well-trained subjects,
particularly those with a resistance training background.
In comparison to past studies that have evaluated
HMB in trained subjects, the findings of the current
study agree with a number of past reports (5, 13, 15, 25,
27), but contrast with others (18, 19, 22) that reported an
increase in some measures of strength in response to
HMB supplementation. The duration of the supplemen-
tation period is an unlikely factor in these differences.
The current study used a 6-week supplementation period,
similar to past studies that used periods of 4–8 weeks of
supplementation. The proposed mechanism of HMB in re-
ducing muscle catabolism and enhancing strength relates
to the ability of HMB either to provide carbon for choles-
terol synthesis or to undergo polymerization and bind co-
valently with cell membrane structures to enhance mem-
brane integrity (18). Further research aimed at elucidat-
ing the physiological mechanism by which HMB functions
may provide a better understanding as to why some
trained subjects respond positively to HMB whereas oth-
ers do not.
The current study also showed no beneficial effect of
HMBCr on muscular strength and endurance, leg power,
or anthropometry. There is strong research evidence that
Cr supplementation can enhance strength and body com-
position (3, 16, 29). Most of these studies, however, uti-
lized a Cr dose of 15–20 g·d?1. The ergogenic effects of Cr
have been shown to be less when supplemented at doses
of 2–3 g·d?1without an initial loading period (8). How-
ever, the ingestion of 3 g·d?1of Cr for 28 days has been
reported to be as effective in raising muscle Cr levels as
a 20 g·d?1loading dose for 6 days, followed by 2 g·d?1for
30 days (9). However, performance measures were not as-
sessed in this study (9). Thus, it is likely that the subjects
in the current study experienced significantly elevated
muscle Cr stores only for the last 2 weeks of the 6-week
supplementation period, which would be insufficient time
for Cr to affect measures of muscular strength and en-
durance. Consistent with this conclusion, past studies
combining HMB and Cr supplementation that reported
positive effects of supplementation on strength and body
composition have utilized higher doses of Cr (15.75–20
g·d?1) (1, 10, 14). The current study utilized a 3 g·d?1dose
of Cr, because this was a commercially available HMB
mix. It is likely that this low dose of Cr, rather than the
fact that Cr was supplemented with HMB, may be the
more likely reason for the lack of ergogenic effect of Cr in
the current study. However, an interaction between the
2 supplements cannot yet be ruled out. Therefore, people
considering standard commercial blends of HMB and Cr
may need to consume additional Cr during an initial load-
ing period of supplementation if the Cr dose is low or they
may need to supplement for longer periods of time.
The training sessions in the current study were fully
supervised and actual loads, as well as sets and repeti-
tions, were determined for each player for each session.
Concurrent resistance and aerobic training may have in-
fluenced the results. However, this is unlikely, because
there were significant improvements in most measures of
muscular strength and endurance from pre- to postsup-
plementation in all groups. This improvement illustrated
that physiological adaptations to resistance training oc-
curred as a result of the 6-week training regime.
It is possible that the relatively short 6-week training
and supplementation period utilized in the current study
limited the potential gains in strength. However, past re-
search reporting positive effects of HMB on strength and
lean body mass utilized supplementation periods of 4–8
weeks (17–19, 30). The current study, therefore, supple-
mented for 6 weeks in order to evaluate if the equivocal
data that existed for HMB was due to a variation in train-
ing background rather than to a difference in the dura-
tion of supplementation. Future research needs to consid-
er longer-term HMB and HMBCr supplementation in
both trained and untrained individuals.
In conclusion, HMB and HMBCr had no effect on the
muscular strength and endurance, leg power, or anthro-
pometry of highly trained athletes undergoing a resis-
tance training program over a 6-week period. The results
of the current study are limited to highly trained male
athletes, and little research exists in female athletes.
Therefore, it would be of interest to substantiate these
findings in a female athlete population. It also would be
HMB AND HMB/CREATINE SUPPLEMENTATION Download full-text
of interest to determine the effects of both HMB and
HMBCr in athletes undergoing resistance training in iso-
lation who are not concurrently participating in other
This study aimed to evaluate the effects of 6 weeks of
dietary supplementation of HMB with and without Cr on
the strength, muscular endurance, leg power, and an-
thropometry of highly trained athletes. There was no ef-
fect of HMB or HMBCr on any of the measured param-
eters when compared with presupplementation measure-
ments or with the control group for this particular group
of athletes. These findings are consistent with other stud-
ies investigating the effects of HMB on strength and body
composition in highly trained athletes (5, 13–15, 23, 25,
27). Thus, the anticatabolic effects of HMB may be limited
in individuals with an extensive resistance training his-
tory. The combination of Cr with HMB also was ineffec-
tive in the current study. It is likely that Cr had no effect
on the measured parameters, as a result of the low dose
taken over the 6-week period without a loading dose. Cre-
atine monohydrate has been shown to be effective when
a loading dose is employed or a lower dose is taken for a
longer period of time (3, 11, 18, 31). With this in mind,
people should be aware of the doses of various supple-
ments contained in commercial supplement blends and
should modify these doses accordingly.
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Address correspondence to D. O’Connor, d.o’connor@