Strength training and weight loss

Abstract

The aims of this study were (a) consider the effectiveness of strength training (ST) to weight loss and (b) present the main physiological me-chanisms that explain this relationship. Through literature review, analyzed studies published originally in international language. As the search strategy was used the Medline database (National Library of Medicine) with the combination of the following keywords: resistance exercise, strength training, weight exercise, strength exercise, energy expenditure, weight loss. No results were found involving concurrent or aerobic exercises. The selected studies show that the ST can effectively collaborate with the weight loss process as a complement to aerobic exercise training and diet. Mentioned cooperation occurs mainly through the increase or maintenance in the resting metabolic rate, energy expenditure of the activity itself and also under the effect related to excessive oxygen consumption after exercise. Moreover, in general, ST periodization is ideal for long-term success because it enables combinations of the beneficial effects of ST-related weight loss.

Full text

Physical Education / Educação Física
J Health Sci Inst. 2010;28(4):337-40 337
Strength training and weight loss
Treinamento de força e emagrecimento
Gustavo Ribeiro da Mota1, Fábio Lera Orsatti1, Tatienne Neder Figueira da Costa2,3, Moacir Marôcolo Júnior1
1Department of Sport Sciences, Federal University of Triângulo Mineiro, Uberaba-MG, Brazil; 2Nursing School, University Center of Votu-
poranga, Votuporanga-SP, Brazil; Physical Education School, University Center of Votuporanga, Votuporanga-SP, Brazil.
Abstract
The aims of this study were (a) consider the effectiveness of strength training (ST) to weight loss and (b) present the main physiological me-
chanisms that explain this relationship. Through literature review, analyzed studies published originally in international language. As the
search strategy was used the Medline database (National Library of Medicine) with the combination of the following keywords: resistance
exercise, strength training, weight exercise, strength exercise, energy expenditure, weight loss. No results were found involving concurrent
or aerobic exercises. The selected studies show that the ST can effectively collaborate with the weight loss process as a complement to
aerobic exercise training and diet. Mentioned cooperation occurs mainly through the increase or maintenance in the resting metabolic rate,
energy expenditure of the activity itself and also under the effect related to excessive oxygen consumption after exercise. Moreover, in
general, ST periodization is ideal for long-term success because it enables combinations of the beneficial effects of ST-related weight loss.
Descriptors: Exercise; Weight lifting; Resistance training; Weight loss; Obesity
Resumo
Os objetivos deste trabalho foram (a) analisar a eficácia do treinamento de força muscular (TF) sobre o emagrecimento e (b) apresentar os
principais mecanismos fisiológicos que explicam tal relação. Por meio de revisão de literatura foram analisados estudos publicados original-
mente em idioma internacional. Como estratégia de busca, foi utilizada a base de dados Medline (National Library of Medicine) com a com-
binação das seguintes palavras-chave: resistance exercise, strength training, weight exercise, strength exercis, energy expendidture, weight
loss. Não foram considerados resultados que implicavam em exercícios concorrentes ou aeróbios. Os trabalhos selecionados mostram que o
TF pode efetivamente colaborar com o processo de emagrecimento como complemento ao treinamento aeróbio e à dieta. Citada cooperação
ocorre, principalmente, por meio do aumento ou manutenção na taxa metabólica de repouso, do gasto energético da própria atividade de
força e também pelo efeito relacionado ao consumo de oxigênio excessivo após o exercício. Além disso, de forma geral, a periodização do
TF é ideal para o sucesso em longo prazo, pois possibilita combinações dos efeitos benéficos do TF relacionados ao emagrecimento.
Descritores: Exercício; Levantamento de peso; Treinamento de resistência; Perda de peso; Obesidade
Introduction
Muscle strength is the capacity of the neuromuscular system to
win or to oppose the external resistance such as weights, elastic
bands, the very body mass and strength training machines. The syste-
matic implementation of such exercise is called strength training (ST)
and has a positive impact in several activities of daily living. This
benefit is obvious because these activities require a certain percentage
of the individual capacity to perform tasks and improvement in muscle
strength result in less physiological stress to implement them1.
The ST, also called resistance training or weight training has been
considered an important component of exercise programs aimed at
physical fitness and health2. This link occurs by the association of
the metabolic effects caused by the loss of muscle mass to the high
prevalence of obesity, insulin resistance, type 2 diabetes, dyslipide-
mia and hypertension3. Conversely, the gain and/or the preservation
of muscle mass through the ST, has been regarded as formidable
factor in preventing or combating the harmful effects of aging2.
On the other hand, excess of body fat is related to various diseases
and its prevalence has increased significantly in recent decades4. By
definition, the weight loss occurs when there is reduction of body fat
relative to total body mass. That is, the percentage of body fat is de-
creased and this condition is positive for the promotion of health5.
Traditionally, the predominant aerobic exercise training has been
recommended as priority by the international scientific community
when it comes to exercise and weight loss5. This suggestion probably
is based on the higher oxygen consumption (VO2) (and energetic
expenditure) than the aerobic activities have compared the strength
for the same time of exercise1,6 together with the fact of the aerobics
oxidize more lipids when compared to ST, which predominantly
use carbohydrate as fuel energy for its accomplishment. However,
more recent studies have suggested that ST plays an important role
in controlling body weight and results in unique effects that the im-
plementation of aerobic exercise alone can not achieve6.
We analyzed the most relevant studies published originally in in-
ternational language. As the search strategy was used the database
Medline (National Library of Medicine) with the combination of
the following keywords: resistance exercise, strength training, weight
exercise, strength exercise, energy expenditure, weight loss. No re-
sults were considered if involving aerobic or concurrent exercises.
Thus, the aims of this review were (a) analyze the effectiveness
of ST on the weight loss process and (b) present the main physiolo-
gical mechanisms that explain this.
Discussion
Energy balance
The change in body mass is explained mathematically by ±
95% of cases. Less than 5% occur from hereditary diseases that
cause obesity or slimness7. Thus, the weight loss occurs when
there is negative energy balance. That is, the total daily energy ex-
penditure (TEE) exceeds your energy consumption. Conversely,
when caloric intake exceeds the TEE, there will be a condition of
positive energy balance, with subsequent gain in body mass. If
both (TEE and food intake) are equal to the body mass1mainte-
nance will occur (Table 1).
Table 1. Balance energy and implications for body mass
Input energy Output energy Result on body mass
Equal Equal No change
Higher Minor Increase
Minor Higher Decrease

Components of total daily energy expenditure
Considering that weight loss will happen if the TTE is greater than
the calorie intake (Table 1), it is imperative to understand how the
body spends energy in the twenty-four hours. Basically there are
three components: (a) resting metabolic rate, which involves energy
expenditure to maintain physiological functions during sleep and in
situations close to the resting state. It is estimated that approximately
60-75% of TTE is devoted to this component, (b) thermic effect of
food which is the component responsible for digestion, absorption
and assimilation of nutrients from foods eaten with ± 10% of TTE
and (c) thermic effect of physical activity that is ± 15 to 30% of TTE1
(Table 2). Clearly, these values are approximate and that there are al-
ways individual variations. That said, we will look from here the
effect of ST on each of these components through the literature.
Table 2. Estimated values of total daily energy expenditure
Components Energy expenditure
Resting metabolic rate ± 60 a 75%
Thermic effect of food ± 10%
Thermic effect of physical activity ± 15 a 30%
Prescription of strength training and weight loss
Whereas the resting metabolic rate is the major component of the
TTE and that it relates to the amount of individual muscle mass8, the
hypothesis that the ST to provide muscle hypertrophy contributes to
the process of weight loss5. Logically this physiological effect (hy-
pertrophy) not only depend on the training itself, but also on other
factors such as genetics, and action hormonal9and nutrition2,10.
The postulated mechanism for the collaboration of the ST with
weight loss via muscle hypertrophy, it would be this: the increase
in muscle mass creates greater resting metabolic rate and this, in
turn, increases the TTE, thereby reducing the fat corporal5.
As noted above, muscle hypertrophy depends not only on phy-
sical training. Nevertheless, for purposes of this study will focus on
the major aspects of the prescription of ST that could maximize
hypertrophy and, thus, contribute to the negative energy balance.
Intensity
The ideal intensity (weight used) of ST to stimulate and generate
hypertrophy has been a subject of great curiosity among researchers.
In general, it is recommended that a weight falls between 6 and 12
repetitions maximum (RM)11 or ± 70 to 90% 1RM2. Importantly,
small variations in these values also stimulate muscle hypertrophy,
but with a lower rate hypertrophic.
An interesting study looked at three groups of ST with different
protocols (4 sets of 3 to 5RM; 3 sets of 9 to 11RM and 2 sets of 20
to 28RM) for eight weeks and found that all groups improved ma-
ximal strength (1RM) and muscular endurance (maximum number
of repetitions with 60% 1RM) in relation to control group and also
to their own values of the pre-training. With regard to muscle hy-
pertrophy, all training groups, except the “high repetitions” improved
compared to its pre-training values and control. These results suggest
that almost all combinations of the components of ST generate be-
nefits (strength, power, endurance, hypertrophy), but that certain
combinations of variables that make up the ST emphasize more (or
less) such results due to the specificity of training11.
Pause between sets
Pauses or rest intervals between sets can modify the metabolic
stress of ST and thus the chronic adaptations provided by the ST.
For example, short intervals (± 45 sec to 1 min 30 sec) further sti-
mulate the lactic anaerobic system, while long pauses (± 3-5 min),
by allowing more creatine phosphate12 regeneration, stress less the
same bioenergetic system . How high blood lactate values are re-
lated to the release of anabolic hormones such as testosterone and
GH, and greater hypertrophy muscular13 the recommendation for
shorter pauses is useful for the purpose of increasing the resting
energy expenditure due to increased muscle mass.
Muscle actions
Concentric muscle actions, eccentric and isometric muscle strains
produce different results and therefore in different training effects.
In general, when isolated, the eccentric muscle action is the one
that generates micro lesions compared to others14. These small le-
sions are called adaptive micro-trauma and are fundamental to sti-
mulate muscle hypertrophy. However, in practice the ST, all types
of muscle actions are performed with, once again, different emp-
hases depending on the training method.
Speed of movement
Relatively recent works show that the fast movement of exercise
promotes greater stimulus for muscle hypertrophy than slower15.
Thus, the periodization of ST should also consider this variable
(speed of movement) in the different cycles of training and promo-
ting changes to better stimulate the muscles constantly requested.
Increase resting metabolic rate
It is believed that the main mechanism by which ST contributes
significantly to the weight loss process is the increase in resting
metabolic rate and, finally, TTE5. As the largest component of TEE
is the resting metabolism and the main energy substrate used in
this situation is the fat, this would be an efficient way to promote
weight reduction and, ultimately, the body fat. However, is neces-
sary to understand that the caloric expenditure (kcal) by increased
muscle mass is modest when viewed daily. It has been estimated at
30 to 50 kcal/day in the resting metabolic rate for 1 kg of muscle
mass acquired16. Furthermore, incorporating 1 kg of muscle mass
does not occur quickly, nor is it as simple as it depends not only on
ST. Nevertheless, long-term (one year, for example), these low
values would generate daily reduction from 1.42 to 2.37 kg of
body fat. Seen in this light, the ST and its chronic effect on muscle
mass appear to be extremely healthy for weight loss.
A study compared ST with the endurance and concurrent (concur-
rent endurance and ST) in physically active men, for ten weeks. Before
and after the intervention, among other parameters, the authors reported
greater increases in basal metabolic rate with ST than endurance. Mo-
reover, changes in lean mass was related to change in this rate17.
Another study that found positive changes in TTE after 26 weeks
of ST was conducted in older of both sexes. In this case, these authors
found increases in strength (36%) and resting energy expenditure
(6.8%) and decreased respiratory quotient of ± 3.5% which means
increased fat oxidation at rest18. In the same line of work mentioned,
but investigating elderly with coronary artery disease, has been re-
ported that ST increases the TTE after 6 months with a 4% increase
in resting metabolic rate measured by indirect calorimetry19.
Aiming to compare the TEE and nutrient oxidation in 24 hours,
research carried out with ten men on three different occasions
(cycle ergometer at 70% VO2max; ST circuit at 70% 1RM and con-
trol) concluded that both TTE as the oxidation of macronutrients of
ST was similar to that of aerobic exercise and superior to control20.
Recently, randomized study of two groups (control and ST) sho-
wed that only a set of 3-6RM (9 exercises, 3 days/week, 6 months)
significantly increased resting and sleep metabolic rates, and in-
creased oxidation fat during sleep in young21. The impressive is
that the total time of the session was only 11 ± 1 min, which
reveals to be suitable for people who have little time to exercise
and need or want to improve body composition.
Energy expenditure with strength training itself
The energy expenditure provided by the ST is considered relati-
vely small when compared to aerobic exercises. Because aerobic
can run for longer periods and often recruit more muscle mass,
they require higher VO2and promote, thereby, higher energy ex-
penditure6. For example, a 70 kg person running at 6 mph for 30
minutes ± 338 kcal spend while during the same period, the ST
spent between 60 and 150 kcal whereas a ratio of 15 and 15 min
of exercise min breaks due intermittent nature of ST1.
338 J Health Sci Inst. 2010;28(4):337-40
Mota GR, Orsatti FL, Costa TNF, Marôcolo Júnior M.

A research was conducted to compare the energy expenditure
of aerobic activity to ST with relatively similar time and intensity.
Ten youths trained both held on separate days (crossover design)
30 min of continuous cycle ergometer (± 70% VO2max) and 30
min of intermittent squat (± 70% of 1RM). Energy expenditure was
higher for the aerobic situation (441 ± 17 kcal) versus the ST (269
± 13 kcal). However, the author concludes that although energy
expenditure was lower in ST, this mode of exercise produced an
expenditure for interest for the purpose of health and, chronically,
unique benefits that only aerobics would not enable, such as power,
endurance and muscular strength6. Importantly, a limitation of study
is that the author did not match the duration of movement execution
of ST, as it was intermittent, the total time spent on this exercise
was lower (6.21 ± 1.3 minutes ) compared to the aerobic (30 mi-
nutes). Furthermore, the intensities used can not be considered the
same (70% 1RM versus 70% VO2max), as they have very different
metabolic behaviors, whereas 70% 1RM represents an intensity
well above the anaerobic threshold6.
Another aspect to consider is that, according to Scott22 (2002),
VO2during the ST does not properly reflect the energy expenditure,
since factors such as occlusion of blood flow during intense mus-
cular contraction and the absence of steady-state "reflect limitation
of VO2to quantify energy expenditure in ST. Thus, the caloric ex-
penditure would be underestimated for this type of exercise when
the VO2is used and blood lactate concentration would be more
appropriate for this aims22.
Strength training and EPOC
The excessive oxygen consumption after exercise (EPOC) refers
to the greater use of this gas relative to resting values, soon after
physical exercises. Interestingly, the return of VO2to the rest pattern
can take anywhere from a few minutes23 until to several hours24.
The basical and traditional explanation for EPOC occurrence in-
volve regeneration of creatine phosphate, lactate removal and hor-
mones, restoring the muscle stores of oxygen and return tempera-
ture, as well as heart and respiratory rates to resting values. It has
also made clear in the literature, is the fact that more intense exer-
cise provides greater EPOC when compared to less intense25. As
the VO2is related to energy expenditure, physical activities that
provide greater EPOC would be contributing more to raise the TTE
and, thus, potentiate to the weight loss.
Accordingly, studies have been conducted to investigate the
effect of ST on EPOC. One showed that 45 minutes of ST in trained
young women created a greater EPOC and fat oxidation during the
2 hours after ST than control day measures26.
Other authors24 reported that EPOC can last up to 38 hours after
a single session of high intensity of ST in healthy men and young
(31 min circuit, four passages in bench press, dead lift and squat,
with 10RM until momentary concentric failure). Undoubtedly these
positive findings raise hypotheses about the real efficacy of ST in
the process of weight loss by means of EPOC, and shows that
values from previous studies27 (16 hours) were much lower.
When the ST occurs in the circuit, the pause between each
station must also be considered. Haltom et al.28 (1999) compared
20 versus 60 seconds (both eight exercises with 75% from 20RM)
and saw that the EPOC was greater for the slightest pause (10.3 ±
0.6 L.min-1) compared the largest (7.4 ± 0.4 L.min-1). This finding
also demonstrates the effect of intensity on EPOC, since the interval
between sets is a variable that determines the intensity in ST. Inte-
restingly, although the EPOC was higher with the slightest pause,
when the total energy expenditure (exercise + recovery) was com-
puted, the protocol with the highest pause (60 seconds) spent more
energy (277 kcal) than the 20 seconds (242 kcal). Thus, it is impor-
tant to analyze the energy expenditure as a whole (exercise and re-
covery).
Another relevant factor in the control of body mass is the substrate
oxidation that occurs in response to ST. Studies have shown increased
lipid oxidation after a single session of ST when compared to pre-
exercise time and/or group control measures26,29. This is because,
in recovery, the lipids become the predominant fuel to limit the use
of carbohydrate and regenerate depleted glycogen stores in ST30.
Conclusions
Analyzing the studies reviewed, we conclude that strength trai-
ning can actually help weight loss as an excellent complement to
aerobic exercise training and diet. The mechanisms that govern
this process are (a) increasing or maintaining their resting metabolic
rate, (b) increase in total energy expenditure considering their own
strength activity and (c) also the effects related to excessive oxygen
consumption after exercise. Moreover, the periodization of the trai-
ning program appears to be ideal for long-term success because it
allows combinations of the beneficial effects of strength training
related to weight loss.
References
1. ACSM. ACSM's Guidelines for exercise testing and prescription. 7th ed. Phila-
delphia: Lippincott Williams & Wilkins; 2006.
2. American College of Sports Medicine position stand. Progression models in re-
sistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708.
3. Klein S, Burke LE, Bray GA, Blair S, Allison DB, Pi-Sunyer X et al. Clinical im-
plications of obesity with specific focus on cardiovascular disease: a statement
for professionals from the American Heart Association Council on Nutrition, Phy-
sical Activity, and Metabolism: endorsed by the American College of Cardiology
Foundation. Circulation. 2004;110(18):2952-67.
4. Han JC, Lawlor DA, Kimm SY. Childhood obesity. Lancet. 2010;375(9727):
1737-48.
5. Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK. American
College of Sports Medicine Position Stand. Appropriate physical activity interven-
tion strategies for weight loss and prevention of weight regain for adults. Med Sci
Sports Exerc. 2009;41(2):459-71.
6. Bloomer RJ. Energy cost of moderate-duration resistance and aerobic exercise.
J Strength Cond Res. 2005;19(4):878-82.
7. Farooqi IS, Keogh JM, Yeo GS, Lank EJ, Cheetham T, O’Rahilly S. Clinical spec-
trum of obesity and mutations in the melanocortin 4 receptor gene. N Engl J Med.
2003;348(12):1085-95.
8. Stiegler P, Cunliffe A. The role of diet and exercise for the maintenance of fat-
free mass and resting metabolic rate during weight loss. Sports Med. 2006;
36(3):239-62.
9. Adams GR. Invited review: autocrine/paracrine IGF-I and skeletal muscle adap-
tation. J Appl Physiol. 2002;93(3):1159-67.
10. Deldicque L, Theisen D, Francaux M. Regulation of mTOR by amino acids
and resistance exercise in skeletal muscle. Eur J Appl Physiol. 2005;94(1-2):1-10.
11. Campos GE, Luecke TJ, Wendeln HK, Toma K, Hagerman FC, Murray TF et
al. Muscular adaptations in response to three different resistance-training regi-
mens: specificity of repetition maximum training zones. Eur J Appl Physiol.
2002;88(1-2):50-60.
12. Glaister M, Stone MH, Stewart AM, Hughes M, Moir GL. The influence of re-
covery duration on multiple sprint cycling performance. J Strength Cond Res.
2005;19(4):831-7.
13. Goto K, Ishii N, Kizuka T, Takamatsu K. The impact of metabolic stress on hor-
monal responses and muscular adaptations. Med Sci Sports Exerc. 2005;37(6):
955-63.
14. Proske U, Allen TJ. Damage to skeletal muscle from eccentric exercise. Exerc
Sport Sci Rev. 2005;33(2):98-104.
15. Chapman D, Newton M, Sacco P, Nosaka K. Greater muscle damage induced
by fast versus slow velocity eccentric exercise. Int J Sports Med. 2006; 27(8):591-
8.
16. Poehlman ET, Melby C. Resistance training and energy balance. Int J Sport
Nutr. 1998;8(2):143-59.
17. Dolezal BA, Potteiger JA. Concurrent resistance and endurance training in-
fluence basal metabolic rate in nondieting individuals. J Appl Physiol.
1998;85(2):695-700.
18. Hunter GR, Wetzstein CJ, Fields DA, Brown A, Bamman MM. Resistance trai-
ning increases total energy expenditure and free-living physical activity in older
adults. J Appl Physiol. 2000;89(3):977-84.
19. Ades PA, Savage PD, Brochu M, Tischler MD, Lee NM, Poehlman ET. Resis-
tance training increases total daily energy expenditure in disabled older women
with coronary heart disease. J Appl Physiol. 2005;98(4):1280-5.
20. Melanson EL, Sharp TA, Seagle HM, Donahoo WT, Grunwald GK, Peters JC
et al. Resistance and aerobic exercise have similar effects on 24-h nutrient oxida-
tion. Med Sci Sports Exerc. 2002;34(11):1793-800.
J Health Sci Inst. 2010;28(4):337-40 Strength training and weight loss
339

21. Kirk EP, Donnelly JE, Smith BK, Honas J, Lecheminant JD, Bailey BW et al.
Minimal resistance training improves daily energy expenditure and fat oxidation.
Med Sci Sports Exerc. 2009;41(5):1122-9.
22. Scott CB. Contribution of blood lactate to the energy expenditure of weight
training. J Strength Cond Res. 2006;20(2):404-11.
23. Short KR, Sedlock DA. Excess postexercise oxygen consumption and recovery
rate in trained and untrained subjects. J Appl Physiol. 1997;83(1):153-9.
24. Schuenke MD, Mikat RP, McBride JM. Effect of an acute period of resistance
exercise on excess post-exercise oxygen consumption: implications for body mass
management. Eur J Appl Physiol. 2002;86(5):411-7.
25. Thornton MK, Potteiger JA. Effects of resistance exercise bouts of different in-
tensities but equal work on EPOC. Med Sci Sports Exerc. 2002;34(4):715-22.
26. Binzen CA, Swan PD, Manore MM. Postexercise oxygen consumption and
substrate use after resistance exercise in women. Med Sci Sports Exerc. 2001;33
(6):932-8.
27. Osterberg KL, Melby CL. Effect of acute resistance exercise on postexercise
oxygen consumption and resting metabolic rate in young women. Int J Sport Nutr
Exerc Metab. 2000;10(1):71-81.
28. Haltom RW, Kraemer RR, Sloan RA, Hebert EP, Frank K, Tryniecki JL. Circuit
weight training and its effects on excess postexercise oxygen consumption. Med
Sci Sports Exerc. 1999;31(11):1613-8.
29. Henderson GC, Fattor JA, Horning MA, Faghihnia N, Johnson ML, Mau TL et
al. Lipolysis and fatty acid metabolism in men and women during the postexercise
recovery period. J Physiol. 2007;584(Pt 3):963-81.
30. Jamurtas AZ, Koutedakis Y, Paschalis V, Tofas T, Yfanti C, Tsiokanos A et al.The
effects of a single bout of exercise on resting energy expenditure and respiratory
exchange ratio. Eur J Appl Physiol. 2004;92(4-5):393-8.
Corresponding author:
Gustavo Ribeiro da Mota
Department of Sport Sciences
Federal University of Triângulo Mineiro
Av. Frei Paulino, 30 – Abadia
Uberaba-MG, CEP 38025-180
Brazil
E-mail: grmotta@gmail.com
Received July 2, 2010
Accepted September 8, 2010
340 J Health Sci Inst. 2010;28(4):337-40
Mota GR, Orsatti FL, Costa TNF, Marôcolo Júnior M.