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A case for considering age and sex when prescribing rest intervals in resistance training

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Current resistance training position stands recommend that rest interval duration in resistance training should be prescribed based on the training goal and exercise selection. However, these recommendations are mostly extrapolated from studies that included young men as participants. Therefore, they cannot be generalized to all age groups and all resistance training programs. Herein, two overlooked, but possibly important factors for rest interval prescription are discussed: (1) age of the individual and (2) sex. Acute studies indicate that older adults, as compared to young adults, seem to require a shorter duration rest interval to achieve recovery between sets. Due to the differences in fatigability between sexes, it can be speculated that men need a longer duration rest interval when compared to women to maintain high levels of performance. Both sex and age seem to be relevant variables when determining rest interval duration and should not be overlooked by exercise practitioners in program design.
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Ki ne siology 51(2019)1:78- 82Grgic, J. and Schoenfeld, B.J.: A CASE FOR CONSIDERING AGE AND SEX W HEN...
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A CASE FOR CONSIDERING AGE AND SEX WHEN
PRESCRIBING REST INTERVALS IN RESISTANCE TRAINING
Jozo Grgic1 and Brad J. Schoenfeld2
1Institute for Health and Sport (IHES), Victoria University, Melbourne, Australia
2Health Sciences Department, CUNY Lehman College, Bronx, NY
Commentary
Abstract:
Current resistance training position stands recommend that rest interval duration in resistance training
should be prescribed based on the training goal and exercise selection. However, these recommendations
are mostly extrapolated from studies that included young men as participants. Therefore, they cannot be
generalized to all age groups and all resistance training programs. Herein, two overlooked, but possibly
important factors for rest interval prescription are discussed: (1) age, and (2) sex of the individual. Acute
studies indicate that older adults, as compared to young adults, require a shorter duration rest interval to
achieve recovery between sets. Due to the sex differences in fatigability, it can be speculated that men need
a longer duration rest interval than women to maintain high levels of performance. Both sex and age may be
relevant variables when determining rest interval duration in resistance exercise and should not be overlooked
by exercise practitioners in program design.
Key words: intensity; skeletal muscle; repetition maximum; exercise; training; intervals
Introduction
Rest intervals are most commonly dened as the
time dedicated to recovery between sets and exer-
cises (Baechle & Earle, 2000). The current Amer-
ican College of Sports Medicine position stand
(ACSM, 2009) suggests employing longer dura-
tion rest intervals (>three minutes) when training
for muscular strength gains, moderate rest intervals
(60-90 seconds) when training for muscular hyper-
trophy, and short rest intervals (<60 seconds) when
training for muscular endurance. In addition to the
training goal, the position stand suggests that rest
intervals might depend on exercise selection. Longer
rest intervals are recommended for multi-joint
exercises, while shorter rest intervals are deemed
sufcient for single joint exercises (ACSM, 2009).
These guidelines are mostly inferred from studies
that included young men as participants and thus
cannot necessarily be generalized to performance
in women (Ahtiainen, Pakarinen, Alen, Kraemer, &
Häkkinen, 2005; Pincivero, Lephart, & Karunakara,
1997; Robinson, et al., 1995; Willardson & Burkett,
2008). In addition to sex, the age of an individual
might be a consideration when designing training
programs. Specically, some studies suggest that
older individuals might require different resist-
ance exercise prescription when compared to the
young (Bickel, Cross, & Bamman, 2011). There-
fore, current recommendations cannot universally
be generalized to all age groups and all resistance
training programs as several variables need to be
considered when prescribing rest interval duration.
Herein, two overlooked, but likely important factors
for rest interval prescription are discussed: (i) age,
and (ii) sex of the individual.
Age
Age is commonly classied as follows: (i) chil-
dren (0-10 years), (ii) adolescents (10-18 years), (iii)
young adults (19-39 years), (iv) middle-aged adults
(40-64 years), and (v), older adults (≥65 years)
(Grgic, Mikulic, Podnar, & Pedisic, 2017). Acute
studies indicate that rest interval duration needed to
achieve recovery in resistance training might differ
based on the age of the individual. Theou, Gareth,
and Brown (2008) observed that older women (71±4
years), compared to younger women (22±2 years),
required a shorter rest interval duration to obtain full
muscular strength recovery between sets of eight
repetitions (i.e., 30 vs. 60 seconds, respectively).
These ndings are further supported by Bottaro,
Russo, and de Oliveira (2005) who demonstrated
that untrained older men (66±4 years) achieved full
recovery after four repetitions of unilateral knee
Grgic, J. and Schoenfeld, B.J.: A CASE FOR CONSIDERING AGE AND SEX W HEN... Ki ne siology 51(2019)1:78- 82
79
extension exercise by employing a brief rest interval
of 30 seconds, although there was no comparison
with recovery in younger individuals in this study.
Subsequently, Bottaro et al. (2010) carried out a
study that compared differences in recovery rates
between older (80±11 years) and younger untrained
men (24±3 years), and noted that the younger indi-
viduals did not recover fully after one- and two-
minute rest periods when performing three sets of
10 repetitions with an associated decline in peak
torque. However, older men achieved full quadri-
ceps recovery within two minutes of rest. When
comparing fatigability between young (24±2 years)
and older adults (70±5 years), Ditor and Hicks
(2000) reported that older adults were signicantly
less fatigable, as assessed by the voluntary fatigue
index (i.e., the percentage of force reduction from
baseline). Recovery of force might be important
from a muscular strength standpoint as it allows
training with higher loads, which might translate
to higher strength gains due to the principle of
specicity (Mattocks, et al., 2017). Based on these
acute results, it can be surmised that older individ-
uals may require shorter rest intervals to achieve
recovery. Such ndings might in part be explained
by the shift towards an increase in type I bers
and atrophy of type II muscle bers, both reported
to occur with ageing; an event that is occurring
due to a mixture of factors (Charette, et al., 1991).
Type I muscle bers are known to be less fatigable
than type II muscle bers, which might reduce the
recovery needs between sets in resistance training
for older adults (Schiafno & Reggiani, 2011).
The only two longitudinal studies performed in
older adults that compared adaptations to different
rest intervals support the notion that older adults
might benet from shorter rest intervals. Villanueva,
Lane, and Schroeder (2015) used a resistance
training protocol comprised of four to six exercises
per session, performed in two to three sets with four
to six repetitions per set (not performed to muscular
failure). The authors’ observed that training with a
one-minute rest between sets is superior to resting
for four minutes for gains in muscular strength,
body composition, and functional performance.
In resistance-trained older women (66±4 years),
Jambassi Filho et al. (2017) reported no signi-
cant differences in muscle activity, isometric, or
dynamic muscle strength between groups that
rested for one minute and three minutes following
an eight-week resistance training intervention. In
other words, equal effects were observed for both
groups; however, the one-minute rest interval group
had a shorter total training time, thus providing
greater training efciency. While future longitu-
dinal studies comparing adaptations to rest inter-
vals between age groups are warranted, these
initial ndings indicate that older adults might ef-
ciently recover during shorter rest intervals. Shorter
rest intervals will reduce the duration of training
sessions and might facilitate long-term adherence
to resistance training in older adults as lack of time
is commonly cited as the reason for poor exercise
adherence (Heesch & Masse, 2004). However, it
should also be noted that reducing the rest interval
duration can lead to acute increases in the rating
of perceived exertion (Farah, et al., 2012), which
should be taken into account, especially when
working with resistance training naïve individuals.
Sex
In addition to age, sex can also be a modifying
variable in the determination of rest interval dura-
tion. Men and women have different rates of fati-
gability and neuromuscular performance that are
likely due to sex differences in anatomy and physi-
ology (Hunter, 2014). Although based on a limited
sample size, there is evidence that, when compared
to women, men have larger muscles and greater
proportional area of type II muscle bers (Staron,
et al., 2000). These muscle bers are reported to
have a two-fold larger calcium uptake than type I
muscle bers (Li, et al., 2002). There is a signicant
relationship between the proportional area of type II
muscle bers and calcium activity, which together
might be related to muscle mechanics (Gollnick,
Körge, Karpakka, & Saltin, 1991; Hunter, et al.,
1999; Madsen, Franch, & Clausen, 1994). This
could be signicant from a fatigue standpoint, as
some evidence indicates that women have slower
calcium kinetics from the sarcoplasmic reticulum
than men; possibly explaining the sex differences
in fatigability (Hunter, 2014). In addition, for some
muscle groups, women may have greater muscle
perfusion, which can increase blood supply to the
activated muscle during exercise, thus delaying
fatigue and facilitating training with shorter rest
intervals (Hunter, 2014). These physiological differ-
ences, besides the possible differences in lipid
source utilization between sexes (Roepstorff, et al.,
2002), might be the primary reasons why women
are less fatigable than men during both isometric
and dynamic exercise of a similar intensity (Hunter,
2014). Taken together, it could be suggested that sex
is an important variable in exercise prescription.
Acute resistance training studies support this
notion as they indicate that women require shorter
rest intervals between sets to maintain performance
compared to men. This concept is best illustrated
by the work of Ratamess et al. (2012), who reported
that, during an upper-body resistance exercise with
a rest interval of one minute, women were able to
perform 10, nine and eight repetitions during sets
one, two and three, respectively. Men, also resting
for one minute, performed 10, seven and four repe-
titions during the three sets of bench press (Figure
1). Celes et al. (2010) observed similar differences
between men and women for lower body exercise
Ki ne siology 51(2019)1:78- 82Grgic, J. and Schoenfeld, B.J.: A CASE FOR CONSIDERING AGE AND SEX W HEN...
80
(i.e., isokinetic knee extensions), demonstrating
that both males and females required two minutes
of rest between sets to fully recover quadriceps
strength. However, for muscular strength observed
at 180°/s, a re st interval of one minute allowed suf-
cient recovery in women but not in men. Based on
these acute ndings, it can be hypothesized that
women, compared to men, might benet from a
shorter duration rest intervals.
short, and may hinder gains in strength. Nonethe-
less, rest of 80 seconds (which is still shorter than
the three minutes of rest between sets recommended
by the ACSM, 2009) between sets was sufcient to
achieve robust gains in muscular strength.
For men, the opposite seems to be the case. Both
Schoenfeld et al. (2016) and de Salles et al. (2010)
reported that training with a longer rest interval
duration (i.e., three and ve minutes, respec-
tively) was superior for gains in muscular strength
compared to a one-minute rest interval. The nd-
ings for strength are likely explained by more “prac-
tice” with heavier loads in the longer duration rest
interval groups, because, when training with shorter
rest intervals, the load needs to be reduced to main-
tain the desired repetition range. Besides strength,
Schoenfeld et al. (2016) observed greater muscular
hypertrophy (in some, but not all muscle groups) in
the three-minute vs. one-minute rest interval group;
a nding that also contradicts current resistance
training guidelines (ACSM, 2009). These nd-
ings on hypertrophy could be related to a greater
muscle protein synthesis response that occurs
when training with longer duration rest inter-
vals (McKendry, et al., 2016). While the area of
the importance of sex in prescribing rest interval
duration is an interesting one, at present, there
have been no published longitudinal studies that
would directly compare the effects of rest inter-
vals of varying duration on muscular adaptations
between sexes. Thus, this area remains speculative
and should be explored in future studies given the
current paucity of evidence. Future studies might
investigate this issue by including two mixed-sex
groups that would train with different rest intervals,
and sex difference could be explored by plotting the
results separately for men and women.
As the body of evidence continues to increase,
it is essential to revisit and reanalyze current resist-
ance exercise recommendations. It seems that
prescribing rest intervals merely on the training
goal and exercise selection could be too simplistic,
as other factors also need to be taken into account.
While the evidence is still emerging, both age and
sex might be relevant variables that should be consid-
ered in program design. Despite a logical rationale,
longitudinal studies directly exploring this topic
are needed to provide clarity on the topic. Given
the gaps in literature, future research should seek
to compare the effects of rest intervals of varying
duration on muscular adaptations between young
and older individuals. Furthermore, future studies
should endeavor to elucidate how the acute differ-
ences in fatigability between sexes might impact
long-term adaptations to rest intervals of different
durations.
Fig ure 1. Number of completed repetitions by women and men
in the three sets of the bench press exercise with a rest inter val
duration of one minute as presented by Ratamess, et al. (2012).
An unpublished 12-week intervention in 23
untrained women conducted by Reed-Hardison
(1998) showed that the group that trained with
30-second rest intervals increased lower body
strength to a greater extent compared to the group
that trained with 90-second rest intervals. More-
over, upper body strength in the 30-second rest
interval group increased by 40% compared to 30%
in the 90-second rest interval group; albeit, the
differences between the groups for the upper body
did not reach statistical signicance. Although the
study was not published, its methodological aspects
were deemed to be of good quality and similar, or
even of higher quality as compared to the other
peer-reviewed studies on the topic of rest intervals
(Grgic, Schoenfeld, Skrepnik, Davies, & Mikulic,
2018). While women may benet from shorter rest
intervals, it also should be noted that limiting rest
intervals to 20 seconds during a lower-body resist-
ance training program has been shown to produce
inferior muscular strength adaptations compared
to 80-second rest intervals. In a ve-week inter-
vention, Hill-Haas, Bishop, Dawson, Goodman,
and Edge (2007) reported that women who rested
for 20 seconds increased strength by 9%, whereas
those that rested for 80 seconds increased muscular
strength by 46%, even when matched for total
training volume. These ndings suggest that at a
certain point the rest interval duration can be too
Grgic, J. and Schoenfeld, B.J.: A CASE FOR CONSIDERING AGE AND SEX W HEN... Ki ne siology 51(2019)1:78- 82
81
References
Ahtiainen, J.P., Pakarinen, A., Alen, M., Kraemer, W.J., & Häkkinen, K. (2005). Short vs. long rest period between
the sets in hypertrophic resistance training: Influence on muscle strength, size, and hormonal adaptations in
trained men. Journal of Strength and Conditioning Research, 19(3), 572-582.
American College of Sports Medicine (ACSM). (2009). American College of Sports Medicine position stand. Progression
models in resistance training for healthy adults. Medicine and Science in Sports and Exercise, 41(3), 687-708.
Baechle, T.R., & Earle, R.W. (2000). Essentials of strength and conditioning (2nd ed.). Champaign, IL: Human Kinetics.
Bickel, C.S., Cross, J.M., & Bamman, M.M. (2011). Exercise dosing to retain resistance training adaptations in young
and older adults. Medicine and Science in Sports and Exercise, 43(7 ), 1177-1187.
Bottaro, M., Ernesto, C., Celes, R., Farinatti, P.T., Brown, L.E., & Oliveira, R.J. (2010). Effects of age and rest interval
on strength recovery. International Journal of Sports Medicine, 31(1), 22-25.
Bottaro, M., Russo, A.F., & de Oliveira, R.J. (2005). The effects of rest interval on quadriceps torque during an isokinetic
testing protocol in elderly. Journal of Sports Science and Medicine, 4(3), 285 -290.
Celes, R., Brown, L.E., Pereira, M.C., Schwartz, F.P., Junior, V.A., & Bottaro, M. (2010). Gender muscle recovery
during isokinetic exercise. International Journal of Sports Medicine, 31(12), 866-869.
Charette, S.L., McEvoy, L., Pyka, G., Snow-Harter, C., Guido, D., Wiswell, R.A., & Marcus, R. (1991). Muscle
hypertrophy response to resistance training in older women. Journal of Applied Physiology, 70(5) , 1912 -1916.
de Salles, B.F., Simão, R., Miranda, H., Bottaro, M., Fontana, F., & Willardson, J.M. (2010). Strength increases in upper
and lower body are larger with longer inter-set rest intervals in trained men. Journal of Science and Medicine
in Sport, 13(4), 429 -433.
Ditor, D.S., & Hicks, A.L. (2000). The effect of age and gender on the relative fatigability of the human adductor
pollicis muscle. Canadian Journal of Physiology and Pharmacology, 78(10), 781-790.
Farah, B.Q., Lima, A.H., Lins-Filho, O.L., Souza, D.J., Silva, G.Q., Robertson, R.J., …, & Ritti-Dias, R.M. (2012).
Effects of rest interval length on rating of perceived exertion during a multiple-set resistance exercise. Perceptual
and Motor Skills, 115(1), 27 3-282 .
Gollnick, P.D., Körge, P., Karpakka, J., & Saltin, B. (1991). Elongation of skeletal muscle relaxation during exercise
is linked to reduced calcium uptake by the sarcoplasmic reticulum in man. Acta Physiologica Scandinavica,
142 (1), 135-136.
Grgic, J., Mikulic, P., Podnar, H., & Pedisic, Z. (2017). Effects of linear and daily undulating periodized resistance
training programs on measures of muscle hypertrophy: A systematic review and meta-analysis. PeerJ the
Journal of Life and Environmental Sciences, 22, e3695.
Grgic, J., Schoenfeld, B.J., Skrepnik, M., Davies, T.B., & Mikulic, P. (2018). Effects of rest interval duration in resistance
training on measures of muscular strength: A systematic review. Sports Medicine, 48(1), 137-151.
Heesch, K.C., & Mâsse, L.C. (2004). Lack of time for physical activity: Perception or reality for African American
and Hispanic women? Women and Health, 39(3), 45-62 .
Hill-Haas, S., Bishop, D., Dawson, B., Goodman, C., & Edge, J. (2007). Effects of rest interval during high-repetition
resistance training on strength, aerobic fitness, and repeated-sprint ability. Journal of Sports Sciences, 25(6),
619-62 8.
Hunter, S.K. (2014). Sex differences in human fatigability: Mechanisms and insight to physiological responses. Acta
Physiologica, 210(4), 768 -789.
Hunter, S.K., Thompson, M.W., Ruell, P.A., Harmer, A.R., Thom, J.M., Gwinn, T.H, & Adams, R.D. (1999). Human
skeletal sarcoplasmic reticulum Ca2+ uptake and muscle function with aging and strength training. Journal of
Applied Physiology, 86(8), 1858-1865.
Jambassi Filho, J.C., Gurjão, A.L., Ceccato, M., Prado, A.K. G., Gallo, L.H., & Gobbi, S. (2017). Chronic effects of
different rest intervals between sets on dynamic and isometric muscle strength and muscle activity in trained
older women. American Journal of Physical Medicine and Rehabilitation, 96(9), 627-633.
Li, J.L., Wang, X.N., Fraser, S.F., Carey, M.F., Wrigley, T.V., & McKenna, M.J. (2002). Effects of fatig ue and training
on sarcoplasmic reticulum Ca(2+) regulation in human skeletal muscle. Journal of Applied Physiology, 92(3),
912-922.
Madsen, K., Franch, J., & Clausen, T. (1994). Effects of intensified endurance training on the concentration of Na,
KATPase and Ca-ATPase in human skeletal muscle. Acta Physiologica Scandinavica, 150(3), 251-258.
Mattocks, K.T., Buckner, S.L., Jessee, M.B., Dankel, S.J., Mouser, J.G., & Loenneke, J.P. (2017). Practicing the test
produces strength equivalent to higher volume training. Medicine and Science in Sports and Exercise, 49(9),
1945-1954.
McKendry, J., Pérez-López, A., McLeod, M., Luo, D., Dent, J.R., Smeuninx, B., …, & Breen, L. (2016). Short inter-set
rest blunts resistance exercise-induced increases in myofibrillar protein synthesis and intracellular signalling
in young males. Experimental Physiology, 101(7), 866-882.
Pincivero, D.M., Lephart, S.M., & Karunakara, R.G. (1997). Effects of rest interval on isokinetic strength and functional
performance after short-term high intensity training. British Journal of Sports Medicine, 31(3), 229-234.
Ki ne siology 51(2019)1:78- 82Grgic, J. and Schoenfeld, B.J.: A CASE FOR CONSIDERING AGE AND SEX W HEN...
82
Ratamess, N.A., Chiarello, C.M., Sacco, A.J., Hoffman, J.R., Faigenbaum, A.D., Ross, R.E., & Kang, J. (2012). The
effects of rest interval length on acute bench press performance: The influence of gender and muscle strength.
Journal of Strength and Conditioning Research, 26(7), 1817-1826.
Reed-Hardison, B.L. (1998). Comparison of 30 and 90 second rest periods between sets of a resistance training program.
(Master’s thesis, Oklahoma State University). Retrieved from shareok.org/bitstream/handle/11244/12080/Thesis-
1998-R327c.pdf?sequence=1 on September 20, 2017.
Robinson, J.M., Stone, M.H., Johnson, R.L., Penland, C.M., Warren, B.J., & Lewis, R.D. (1995). Effects of different
weight training exercise/rest intervals on strength, power, and high intensity exercise endurance. Journal of
Strength and Conditioning Research, 9(4), 216 -221.
Roepstorff, C., Steffensen, C.H., Madsen, M., Stallknecht, B., Kanstrup, I.L., Richter, E.A., & Kiens, B. (2002). Gender
differences in substrate utilization during submaximal exercise in endurance-trained subjects. American Journal
of Physiology – Endocrinology and Metabolism, 282(2), 435-447.
Schiaffino, S., & Reggiani, C. (2011). Fiber types in mammalian skeletal muscles. Physiological Reviews, 91(4), 1447-
1531.
Schoenfeld, B.J., Pope, Z.K., Benik, F.M., Hester, G.M., Sellers, J., Nooner, J.L., …, & Krieger, J.W. (2016). Longer
inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men. Journal of Strength
and Conditioning Research, 30(7 ), 1805 -1812 .
Staron, R.S., Hagerman, F.C., Hikida, R.S., Murray, T.F., Hostler, D.P., Crill, M.T., …, & Toma, K. (2000). Fiber
type composition of the vastus lateralis muscle of young men and women. Journal of Histochemistry and
Cytochemistry, 48(5), 623- 629.
Theou, O., Gareth, J.R., & Brown, L.E. (2008). Effect of rest interval on strength recovery in young and old women.
Journal of Strength and Conditioning Research, 22(6), 1876 -1881.
Villanueva, M.G., Lane, C.J., & Schroeder, E.T. (2015). Short rest interval lengths between sets optimally enhance body
composition and performance with 8 weeks of strength resistance training in older men. European Journal of
Applied Physiology, 115(2), 295-308.
Willardson, J.M., & Burkett, L.N. (2008). The effect of different rest intervals between sets on volume components
and strength gains. Journal of Strength and Conditioning Research, 22(1), 146-152 .
Submitted: September 21, 2017
Accepted: March 13, 2018
Published Online First: March 25, 2019
Correspondence to:
Jozo Grgic, M.Sc.
Institute for Health and Sport (IHES)
Victoria University, Melbourne, Australia
PO Box 14428, Victoria 8001, Australia
Email: jozo.grgic@live.vu.edu.au
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The purpose of the present study was to analyze the effects of resistance-training (RT) exercise order on muscle strength, hypertrophy, and anabolic hormones in older women. Forty-four older women were randomly assigned to one of three groups: a non-exercise control group (CON, n=15) and two RT groups that performed a 12-weeks RT program in a multi-joint to single-joint order (MJ-SJ, n=14), or in a single-joint to multi-joint order (SJ-MJ, n=15). The RT protocol (3x/week) encompassed eight exercises, with three sets of 10-15 repetitions performed per exercise. 1RM tests were used to evaluate muscle strength; DXA was used to estimate lean soft tissue. Both training groups showed significant and similar increases in muscle strength (MJ-SJ=16.4%; SJ-MJ=12.7%) and mass (MJ-SJ=7.5%; SJ-MJ=6.1%), whereas there were no significant changes in testosterone and IGF-1. The results suggest that both approaches are similarly effective in eliciting morphofunctional improvements in older women.
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Background: Although evidence suggests that resistance training should be prescribed as a method to enhance or maintain physical fitness, these findings are mostly based on research on younger men. Studies investigating responses by sex and age to resistance training, especially in war veterans aged ≥50 years, are lacking. Therefore, the main purpose of this study was to examine whether a 4-week resistance training program would have similar effects on body composition, muscular fitness, and flexibility in men and women aged 50-80 years. Methods: Seven-hundred and sixty-four participants were recruited and categorized into two groups each of men and women aged 50-64 and 65-80 years. The training intervention lasted 4 weeks and consisted of three 60 min sessions per week. All participants were tested for each of the following physical fitness components: body composition, push-ups in 30 s, chair-stands in 30 s, sit-ups in 30 s, and a sit-and-reach test. Results: Over the intervention period of 4 weeks, body weight (p = 0.002) and the percent of fat mass (p < 0.001) decreased, while the percent of lean mass (p < 0.001) in push-ups in 30 s (p < 0.001), chair-stands in 30 s (p < 0.001), sit-ups in 30 s (p < 0.001), and sit-and-reach (p < 0.001) increased. Significant time*age interactions were shown for push-ups in 30 s (F1,763 = 4.348, p = 0.038) and chair-stands in 30 s (F1,763 = 9.552, p = 0.002), where men and women aged 50-64 years exhibited larger time-induced changes compared to their older (65-80 yr) counterparts. Effect sizes were similar between sex- and age-specific groups. Conclusions: The 4-week resistance training produced similar pronounced positive effects on body composition, muscular fitness, and flexibility, while men and women aged 50-64 years displayed significantly larger improvements in upper and lower muscular fitness compared with their 65-80-year-old counterparts.
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Background Rest interval (RI) duration is an important resistance-training variable underlying gain in muscular strength. Recommendations for optimal RI duration for gains in muscular strength are largely inferred from studies examining the acute resistance training effects, and the generalizability of such findings to chronic adaptations is uncertain. Objective The goals of this systematic literature review are: (i) to aggregate findings and interpret the studies that assessed chronic muscular strength adaptations to resistance training interventions involving different RI durations, and (ii) to provide evidence-based recommendations for exercise practitioners and athletes. Methods The review was performed according to the PRISMA guidelines with a literature search encompassing five databases. Methodological quality of the studies was evaluated using a modified version of the Downs and Black checklist. Results Twenty-three studies comprising a total of 491 participants (413 males and 78 females) were found to meet the inclusion criteria. All studies were classified as being of good to moderate methodological quality; none of the studies were of poor methodological quality. Conclusion The current literature shows that robust gains in muscular strength can be achieved even with short RIs (< 60 s). However, it seems that longer duration RIs (> 2 min) are required to maximize strength gains in resistance-trained individuals. With regard to untrained individuals, it seems that short to moderate RIs (60–120 s) are sufficient for maximizing muscular strength gains.
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Background Periodization is an important component of resistance training programs. It is meant to improve adherence to the training regimen, allow for constant progression, help in avoiding plateaus, and reduce occurrence and severity of injuries. Previous findings regarding the effects of different periodization models on measures of muscle hypertrophy are equivocal. To provide a more in-depth look at the topic, we undertook a systematic review of the literature and a meta-analysis of intervention trials comparing the effects of linear periodization (LP) and daily undulating periodization (DUP) resistance training programs on muscle hypertrophy. Materials and Methods A comprehensive literature search was conducted through PubMed/MEDLINE, Scopus, Web of Science, SPORTDiscus, Networked Digital Library of Theses and Dissertations (NDLTD) and Open Access Theses and Dissertations (OATD). Results The pooled standardized mean difference (Cohen’s d) from 13 eligible studies for the difference between the periodization models on muscle hypertrophy was −0.02 (95% confidence interval [−0.25, 0.21], p = 0.848). Conclusions The meta-analysis comparing LP and DUP indicated that the effects of the two periodization models on muscle hypertrophy are likely to be similar. However, more research is needed in this area, particularly among trained individuals and clinical populations. Future studies may benefit from using instruments that are more sensitive for detecting changes in muscle mass, such as ultrasound or magnetic resonance imaging.
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The purpose of this study was to investigate the effects of short rest intervals normally associated with hypertrophy-type training versus long rest intervals traditionally used in strength-type training on muscular adaptations in a cohort of young, experienced lifters. Twenty-one young resistance-trained men were randomly assigned to either a group that performed a resistance training (RT) program with 1-minute rest intervals (SHORT) or a group that employed 3-minute rest intervals (LONG). All other RT variables were held constant. The study period lasted 8 weeks with subjects performing 3 total body workouts a week comprised of 3 sets of 8-12 repetition maximum (RM) of 7 different exercises per session. Testing was carried out pre- and post-study for muscle strength (1RM bench press and back squat), muscle endurance (50% 1RM bench press to failure), and muscle thickness of the elbow flexors, triceps brachii, and quadriceps femoris via ultrasound imaging. Maximal strength was significantly greater for both 1RM squat and bench press for LONG compared to SHORT. Muscle thickness was significantly greater for LONG compared to SHORT in the anterior thigh and a trend for greater increases was noted in the triceps brachii,(p = 0.06) as well. Both groups saw significant increases in local upper body muscle endurance with no significant differences noted between groups. The present study provides evidence that longer rest periods promote greater increases in muscle strength and hypertrophy in young resistance-trained men.
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We conducted a 12-wk resistance training program in elderly women [mean age 69 +/- 1.0 (SE) yr] to determine whether increases in muscle strength are associated with changes in cross-sectional fiber area of the vastus lateralis muscle. Twenty-seven healthy women were randomly assigned to either a control or exercise group. The program was satisfactorily completed and adequate biopsy material obtained from 6 controls and 13 exercisers. After initial testing of baseline maximal strength, exercisers began a training regimen consisting of seven exercises that stressed primary muscle groups of the lower extremities. No active intervention was prescribed for the controls. Increases in muscle strength of the exercising subjects were significant compared with baseline values (28-115%) in all muscle groups. No significant strength changes were observed in the controls. Cross-sectional area of type II muscle fibers significantly increased in the exercisers (20.1 +/- 6.8%, P = 0.02) compared with baseline. In contrast, no significant change in type II fiber area was observed in the controls. No significant changes in type I fiber area were found in either group. We conclude that a program of resistance exercise can be safely carried out by elderly women, such a program significantly increases muscle strength, and such gains are due, at least in part, to muscle hypertrophy.
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Purpose: To determine if muscle growth is important for increasing muscle strength or if changes in strength can be entirely explained from practicing the strength test. Methods: Thirty-eight untrained individuals performed knee extension and chest press exercise for 8 weeks. Individuals were randomly assigned to either a high-volume training group (HYPER) or a group just performing the one repetition maximum (1RM) strength test (TEST). The HYPER group performed 4 sets to volitional failure (~8-12RM) while the TEST group performed up to 5 attempts to lift as much weight as possible one time each visit. Results: Data are presented as mean (90% CI). The change in muscle size was greater in the HYPER group for both the upper and lower body at most but not all sites. The change in 1RM strength for both the upper [difference of -1.1 (-4.8, 2.4) kg] and lower body [difference of 1.0 (-0.7, 2.8) kg for dominant leg] was not different between groups (similar for non-dominant). Changes in isometric and isokinetic torque were not different between groups. The HYPER group observed a greater change in muscular endurance [difference of 2 (1, 4) repetitions] only in the dominant leg. There were no differences in the change between groups in upper body endurance. There were between group differences for exercise volume [mean (95% CI)] of the dominant [difference of 11049.3 (9254.6, 12844.0) kg] leg (similar for non-dominant) and chest press with the HYPER group completing significantly more total volume [difference of 13259.9 (9632.0, 16887.8) kg]. Conclusion: These findings suggests that exercise volume nor the change in muscle size from training contributed to greater strength gains compared to just practicing the test.
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Background: Manipulating rest-recovery interval between sets of resistance exercise may influence training-induced muscle remodeling. The aim of this study was to determine the acute muscle anabolic response to resistance exercise performed with short or long inter-set rest intervals. Methods: In a parallel-group designed study, 16 males completed 4 sets of bilateral leg press and knee extension exercise at 75% of 1RM to momentary muscular failure, followed by ingestion of 25 g of whey protein. Resistance exercise sets were interspersed by 1 min (1 M; n = 8) or 5 min of passive rest (5 M; n = 8). Muscle biopsies were obtained at rest, 0, 4, 24 and 28 h post-exercise during a primed-continuous infusion of L-[ring-(13) C6 ]phenylalanine to determine myofibrillar protein synthesis (MPS) and intracellular signaling. Results: MPS rate increased above resting values over 0-4 h post-exercise in 1 M (76%; P = 0.047) and 5 M (152%; P < 0.001), and was significantly greater in 5 M (P = 0.001). MPS rates at 24-28 h post-exercise remained elevated above resting values (P < 0.05) and were indistinguishable between groups. Post-exercise p70S6K(Thr389) and rpS6(Ser240/244) phosphorylation were reduced in 1 M compared with 5 M, whereas eEF2(Thr56) , TSC2(Thr1462) , AMPK(Thr172) phosphorylation and REDD1 protein were greater in 1 M compared with 5 M. Serum testosterone was greater at 20-40 min post-exercise and plasma lactate greater immediately post-exercise for 1 M vs. 5 M. Conclusions: Resistance exercise with short (1 M) inter-set rest duration attenuated myofibrillar protein synthesis during the early post-exercise recovery period compared with longer (5 M) rest duration, potentially through compromised activation of intracellular signalling. This article is protected by copyright. All rights reserved.
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Purpose: To determine if 8 weeks of periodized strength resistance training (RT) utilizing relatively short rest interval lengths (RI) in between sets (SS) would induce greater improvements in body composition and muscular performance, compared to the same RT program utilizing extended RI (SL). Methods: 22 male volunteers (SS: n = 11, 65.6 ± 3.4 years; SL: n = 11, 70.3 ± 4.9 years) were assigned to one of two strength RT groups, following 4 weeks of periodized hypertrophic RT (PHRT): strength RT with 60-s RI (SS) or strength RT with 4-min RI (SL). Prior to randomization, all 22 study participants trained 3 days/week, for 4 weeks, targeting hypertrophy; from week 4 to week 12, SS and SL followed the same periodized strength RT program for 8 weeks, with RI the only difference in their RT prescription. Results: Following PHRT, all study participants experienced increases in lean body mass (LBM) (p < 0.01), upper and lower body strength (p < 0.001), and dynamic power (p < 0.001), as well as decreases in percentage body fat (p < 0.05). Across the 8-week strength RT phase, SS experienced significantly greater increases in LBM (p = 0.001), flat machine bench press 1-RM (p < 0.001), bilateral leg press 1-RM (p < 0.001), narrow/neutral grip lat pulldown (p < 0.01), and Margaria stair-climbing power (p < 0.001), compared to SL. Conclusions: This study suggests 8 weeks of periodized high-intensity strength RT with shortened RI induces significantly greater enhancements in body composition, muscular performance, and functional performance, compared to the same RT prescription with extended RI, in older men. Applied professionals may optimize certain RT-induced adaptations, by incorporating shortened RI.
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Sex-related differences in physiology and anatomy are responsible for profound differences in neuromuscular performance and fatigability between men and women. Women are usually less fatigable than men for similar intensity isometric fatiguing contractions. This sex difference in fatigability, however, is task specific because different neuromuscular sites will be stressed when the requirements of the task are altered, and the stress on these sites can differ for men and women. Task variables that can alter the sex difference in fatigue include the type, intensity and speed of contraction, the muscle group assessed, and the environmental conditions. Physiological mechanisms that are responsible for sex-based differences in fatigability may include activation of the motor neuron pool from cortical and subcortical regions, synaptic inputs to the motor neuron pool via activation of metabolically-sensitive small afferent fibres in the muscle, muscle perfusion, and skeletal muscle metabolism and fibre type properties. Non-physiological factors such as the sex bias of studying more males than females in human and animal experiments can also mask a true understanding of the magnitude and mechanisms of sex-based differences in physiology and fatigability. Despite recent developments, there is a tremendous lack of understanding of sex differences in neuromuscular function and fatigability, the prevailing mechanisms and the functional consequences. This review emphasises the need to understand sex-based differences in fatigability in order to shed light on the benefits and limitations that fatigability can exert for men and women during daily tasks, exercise performance, training and rehabilitation in both health and disease. This article is protected by copyright. All rights reserved.