VARIATION IN REPETITION RANGES FOR HYPERTROPHY

Evidence-Based Guidel ines

James Krieger, M.S.

Hierarchy of Evidence

Systematic Reviews & Meta-Analyses of RCTs

Randomized Controlled Trials

Observational Research

Anecdote and Tradition

Muscle Growth 101

• When individual muscle fibers increase in size (hypertrophy), the entire muscle grows– There is debate whether hyperplasia (increase in muscle fibers)

occurs in humans

Muscle Fiber Recruitment

• Muscle fibers are recruited when muscles contract

• Two ways to increase muscle fiber recruitment

– Increase the load

– Fatigue (get closer to failure)

• Fibers are generally recruited in the order of type I (slow twitch) to type II (fast twitch)

– Type I fibers are fatigue resistant, and are recruited for low loads

– Type II fibers are easily fatigued and only recruited for higher loads or when you get closer to failure

What Makes Muscles Grow?

What Makes Muscles Grow?

• Mechanical tension on individual muscle fibers– Mechanical forces on the fibers are converted

into chemical signals that create an anabolic signal and increase muscle protein synthesis

– When protein synthesis > degradation, muscle fiber grows

What Makes Muscles Grow?

• Mechanical tension on individual muscle fibers must occur for a sufficient amount of time– Simply recruiting or activating a muscle fiber

is insufficient!• Otherwise a single 1-RM would be sufficient for

muscle growth

Why do muscles grow in response to weight training?

Protein synthesisProtein breakdown

At rest, protein synthesis equals protein breakdown

No change in muscle size

Muscle Tension for Sufficient Time

Protein synthesis exceeds breakdown

Increase in muscle tissue

What Makes Muscles Grow?

What Makes Muscles Grow?

• Metabolic stress???

– Possibly works through ↑ type II fiber recruitment

• ↑ mechanical tension on individual muscle fibers

1. Dankel et al., Eur J Appl Physiol, 117:2125-2135, 2017

What Makes Muscles Grow?

• Muscle damage???

– Evidence against it playing a role in growth

• Muscle damage doesn’t correlate with growth1-2

• Increases in muscle protein synthesis only correlate with growth after attenuation of damage2

• Muscle damage does not enhance strength or size gains3-4

– Evidence for

• Training at long muscle lengths and full ROM, which is more damaging, causes more hypertrophy than training at short lengths5-6

1. Damas et al., Eur J Appl Physiol, 118:485-500, 20182. Damas et al., J. Physiol. 594:5209-5222, 2016

3. Folland et al., Med Sci Sports Exerc., 33:1200-1205, 20014. Flann et al., J Exp Biol., 214:674-679, 2011

5. McMahon et al, Muscle Nerve, 49:108-119, 20146. McMahon et al, J Strength Cond Res, 28:245-255, 2014

Week 0 Week 10 Corrected for Muscle Damage

Genetics: The Ultimate Dictator of Hypertrophy

1. Erskine et al., Eur J Appl Physiol, 110:1117-1125, 2010

Training Variables

• Volume

• Load/Repetitions

• Frequency

• Rest Intervals

• Intensity of Effort

• Exercise Selection

• Tempo

• Intensity Techniques

From the Renaissance Prancerization Video Series

Load/Repetitions

• Very high load, low rep training is inferior for hypertrophy when number of sets are matched

– Due to lower training volume

1. Schoenfeld et al., J Sports Sci Med, 15:715-722, 2016

3 2,7

44,9

3

10,4

0

2

4

6

8

10

12

Biceps Triceps Quads

% In

crea

se in

Mus

cle

Thic

knes

s

3 x 2-4 RM 3 x 8-12 RM

Load/Repetitions

• When volume is matched, muscle gains are similar between very high loads (<6 reps) and more moderate loads (8-12 reps)– Moderate loads are more efficient and lower injury risk

1. Schoenfeld et al., J Strength Cond Res, 28:2909-2918, 20142. Klemp et al., Appl Physiol Nutr Metab, 41(7):699-705, 2016

15,2

19

4,9

9,9

12,714,3

5,4

13,7

02468

101214161820

Chest Lateral DistalQuad

Lateral MedialQuad

Anterior Quad

% In

crea

se in

Mus

cle

Thic

knes

s

8-10 sets of 2-6 reps 4-5 sets of 8-12 reps

No statistically significant differences between groups

12,2 12,2

0

2

4

6

8

10

12

14

Biceps

% In

crea

se in

Mus

cle

Thic

knes

s

7 x 3 RM 3 x 8-12 RM

Load/Repetitions

• As long as sets are taken to failure or near-failure, there is no difference in muscle gains between moderate to heavier loads (8-19 reps) and lighter loads (20-40 reps)

– There may be practical differences for some exercises (e.g., deadlifts, squats, etc.)

5,36

9,38,6

5,2

9,5

0

2

4

6

8

10

Biceps Triceps Quads% C

hang

e in

Mus

cle

Thic

knes

s

3 x 8-12 RM 3 x 25-35 RM

1. Schoenfeld et al., J Strength Cond Res, 29:2954-2963, 20152. Schoenfeld et al., J Strength Cond Res, 31:3508-3523, 2017

>60% 1-RM≤60% 1-RM

Load/Repetitions

• When a set is taken to failure or near-failure, all muscle fibers will get trained

– Only the pattern of recruitment is different

1. Dankel et al., Eur J Appl Physiol, 117:2125-2135, 2017

Can Different Rep Ranges Target Different Fiber Types?

• Some research has shown greater type II hypertrophy with lower rep/heavier weight training, and greater type I hypertrophy with higher rep/lighter weight training

– Caveat: Light weights were typically not taken to failure in these studies; rather, work was equated with the low rep groups

– Caveat: Subjects were untrained

1. Netreba et al., Ross Fiziol Zh Im I M Sechenova, 99(3):406-416, 20132. Vinogradova et al., Fiziol Cheloveka, 39(5):71-85, 2013

Can Different Rep Ranges Target Different Fiber Types?

• Mitchell et al. observed a non-significantly larger increase in type I fiber size in a group doing 30% 1-RM to failure versus 80% 1-RM to failure in untrained subjects

1. Mitchell et al., J Appl Physiol, 113:71-77, 2012

161817

30

0

5

10

15

20

25

30

35

80% 1-RM 30% 1-RM

% Change in Fiber Size

Type II Hypertrophy Type I Hypertrophy

Can Different Rep Ranges Target Different Fiber Types?

• Similar improvements in type I and type II fiber CSA when comparing 8-12 RM and 20-25 RM in trained subjects

1. Morton et al., J Appl Physiol, 2016

Can Different Rep Ranges Target Different Fiber Types?

• Bjornsen et al. observed specific type I hypertrophy in powerlifters performing vascular occlusion training

– Might vascular occlusion change recruitment patterns to emphasize type I fibers?

• Might be most noticeable in powerlifters due to their style of training (primarily low rep/heavy load)…perhaps it may not be as relevant to bodybuilding-style training

1. Bjornsen et al., Med Sci Sports Exerc, 51(2):288-298, 2019

Load/Repetitions

• Hypertrophy starts to decrease with loads of ≤20% 1-RM

1. Lasevicius et al., Eur J Sport Sci, Mar 22, 2018 [Epub ahead of print]

Periodization of Reps/LoadStudy Periodization Models

ComparedRepetition Range

Outcome A Outcome B Outcome C Notes

Simao et al. 2012

LinearUndulating

3-15 RM NONLINEAR+4.3% tricep+9.1% bicep

LINEAR+0.7% tricep+5.7% bicep

No significant differences between groups, but only non-linear was significantly greater than control group after training

Pelzer et al. 2017

LinearUndulating

6-15 LINEAR+18.8% proximal VL+18.1% mid VL+21.4% distal VL+15.5% RF+18.5% average

UNDULATING+14.1% proximal VL+16.8% mid VL+ 18.8% distal VL+11.1% RF+15.2% average

No significant differences between groups

Schoenfeld et al. 2016

Constant (8-12 RM)

Varied (Day 1: 2-4 RMDay 2: 8-12 RMDay 3: 20-30 RM)

2-30 CONSTANT+5.0% bicep+4.2% tricep+8.6% VL

VARIED+6.6% bicep+6.4% tricep+7.6% VL

No significant differences between groups. While % gain and effect sizes favored VARIED for bicep and tricep, analysis of individual results reveal this was due to a single outlier in both cases

Souza et al. 2014

Constant (2-3x8)LinearUndulating

6-12 CONSTANT+5.1% quad CSA

LINEAR+4.6% quad CSA

UNDULATING+5.2% quad CSA

No significant differences between groups

Kok et al. 2009

LinearUndulating

6-10 RM LINEAR+8.7% RF CSA

UNDULATING+14.8% RF CSA

No significant differences between groups

Fink et al. 2016

High load (3 x 8-12 RM)Low Load (3x30-40 RM)Mixed Load (2 weeks of each)

8-40 RM HIGH+9.1% bicep CSA

LOW+9.4% bicep CSA

MIXED+8.8% bicep CSA

No significant differences between groups

No clear advantage to periodizing or varying repetition ranges over time

Periodization of Reps/Load

3,93,5

4,75,1

1,9

8,3

0

2

4

6

8

10

12

All Studies Indirect Hypertrophy Measures Direct Hypertrophy Measures

% C

hang

e in

Mus

cle

Size

Linear Periodization vs. Daily Undulating PeriodizationMeta-Analysis of 13 Studies

LP DUP

1. Grgic et al., PeerJ, 5:e3695, 2017

Periodization of Reps/Load

Load/Repetitions: Summary

• Very high load/low rep training is inferior for hypertrophy due to lower volume

– Prolonged periods of high load/low rep training, such as in linear periodization schemes, may not be optimal

• Better to incorporate more frequent variation (intrasession, daily, or weekly) if you incorporate high load/low rep training into a hypertrophy program

• No differences in hypertrophy between moderate loads/reps (8-19) and light loads/high reps (20-30) if sets are taken to failure or near failure

– Hypertrophy begins to diminish at loads ≤20% 1-RM

– High rep sets for compound movements like squats, or low rep sets for isolation movements may not be practical or safe

• No consistent evidence that variation in rep ranges will increase hypertrophy over constant rep schemes

– Evidence whether different rep ranges or vascular occlusion can target specific fiber types is inconclusive

– Biggest benefit may be in reducing joint stress/injury risk, and improving motivation through increased variation

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