Table 1.
Summary of the findings from the studies comparing high and low-load training and its effects on muscle fiber hypertrophy adaptations.
| Reference | Study design | Resistance training exercise(s) | Training frequency and study duration | Method of fiber typing | Results | Relative effects (%)* |
|---|---|---|---|---|---|---|
| Campos et al., 2002 | Young untrained men (n = 27) were allocated either to a high-load group (3–5 RM) a moderate-load (9–11 RM) or a low-load group (20–28 RM). | Squat, leg press, and knee extension | 2–3 times per week; 8 weeks | mATPase histochemistry | Significant pre- to post-intervention increases in type I, type IIa and type IIx muscle fibers were reported in the high-load and moderate-load groups. No significant increases across muscle fiber types were reported for the low-load group. | Type I fibers: High-load = +12 Moderate-load = +13 Low-load = +10 Type IIa fibers: High-load = +23 Moderate-load = +16 Low-load = +8 Type IIx fibers: High-load = +25 Moderate-load = +27 Low-load = +14 |
| Dons et al., 1979 | Young untrained men (n = 12) were allocated either to a high-load group (80% 1 RM) or a low-load group (50% 1 RM). | Squat | 3 times per week; 7 weeks | mATPase histochemistry | No significant pre- to post-intervention increases in muscle fiber size were reported. | Not presented |
| Jackson et al., 1990 | Young untrained men (n = 12) were allocated either to a high-load group (4 RM) or a low-load group (15–25% 1 RM). | Knee extension | 4 times per week; 7.5 weeks | mATPase histochemistry | Both high-load and low-load groups increased the size of all muscle fiber types following the first treatment. Participants that performed high-load training as their second treatment showed further increases in the size of type I and type IIx muscle fibers. In contrast, those performing low-load training as their second treatment showed decreases in the size of all fiber types. | Not presented |
| Lamas et al., 2010 | Young untrained men (n = 22) were allocated either to a high-load group (4–10 RM) or a low-load group (30–60% 1 RM). | Squat | 3 times per week; 8 weeks | mATPase histochemistry | Significant pre- to post-intervention increases in type IIa, and type IIx muscle fibers both for the high-load and low-load groups with no significant between-group differences. The high-load group increased type I muscle fiber size, in contrast to the low-load group, in which, a decrease in the size of type I muscle fiber was reported. | Type I fibers: High-load = +15 Low-load = −5 Type IIa fibers: High-load = +18 Low-load = +15 Type IIx fibers: High-load = +41 Low-load = +19 |
| Mackey et al., 2011 | Young untrained men (n = 12) were allocated either to a high-load group (70% 1 RM) or a low-load group (15.5% 1 RM). | Knee extension | 3 times per week; 12 weeks | mATPase histochemistry | No significant pre- to post-intervention increases in muscle fiber size were reported in either group. | Type I fibers: High-load = −2 Low-load = +1 Type II fibers: High-load = −1 Low-load = −5 |
| Mitchell et al., 2012 | Young untrained men (n = 18) were allocated either to one of two high-load groups (80% 1 RM) or a low-load group (30% 1 RM). | Knee extension | 3 times per week; 10 weeks | mATPase histochemistry | Significant pre- to post-intervention increases in the size of both type I and type II muscle fibers, with no significant between-group differences. | Type I fibers: High-load = +16 High-load = +14 Low-load = +23 Type II fibers: High-load = +16 High-load = +18 Low-load = +12 |
| Morton et al., 2016 | Young trained men (n = 49) were allocated to a high-load group (75–90% 1 RM) or a low-load group (25–50% 1 RM). | Seated row, bench press, shoulder press, front plank, bicep curls, triceps extension, wide grip pull-downs, leg press, knee extension, and knee flexion. | 4 times per week; 12 weeks | Antibody method | Significant pre- to post-intervention increases in the size of both type I and type II muscle fibers, with no significant between-group differences | Type I fibers: High-load = +13 Low-load = +11 Type II fibers: High-load = +18 Low-load = +14 |
| Netreba et al., 2013 | Young untrained men (n = 14) were allocated either to a high-load group (85–90% 1 RM) a moderate-load (60–70% 1 RM) or a low-load group (20–25% 1 RM). | Leg press | 3 times per week; 8 weeks | Antibody method | In the high-load groups, significant pre- to post-intervention increases in all muscle fiber types occurred. In the low-load group, significant pre- to post-intervention increases occurred in type I but not in type II muscle fibers. The high-load group increased the size of type II muscle fibers to a greater extent than the low-load group. The moderate-load group increased the size of both fiber types equally. The low-load group increased type I muscle fibers to a greater extent than the high-load group. | Type I fibers: High-load = +10 Moderate-load = +11 Low-load = +18 Type II fibers: High-load = +20 Moderate -load = +13 Low-load = +8 |
| Schuenke et al., 2012 | Young untrained women (n = 27) were allocated either to a high-load group (6–10 RM), high-load, low-velocity group (6–10 RM) or a low-load group (20–30 RM). | Squat, leg press, and knee extension | 2–3 days per week; 6 weeks | mATPase histochemistry | Significant pre- to post-intervention increases in type I, type IIA and type IIX muscle fibers for the high-load group. Significant pre- to post-intervention increases in type IIa, and type IIx muscle fibers were reported for the high-load, low-velocity group. No significant increases in muscle fibers were reported for the low-load group. | Type I fibers: High-load = +26 High-load low-velocity = +6 Low-load = 0 Type IIa fibers: High-load = +31 High-load low-velocity = +12 Low-load = +9 Type IIx fibers: High-load = +37 High-load low-velocity = +19 Low-load = +9 |
| Taaffe et al., 1996 | Older untrained women (n = 14) were allocated either to a high-load group (80% 1 RM) or a low-load group (40% 1 RM). | Leg press, knee flexion, and knee extension | 3 days per week; 52 weeks | mATPase histochemistry | Significant pre- to post-intervention increases in type I, muscle fibers for the high-load and low-load group. No significant pre- to post-intervention increases were reported for type II muscle fibers. | Type I fibers: High-load = +28 Low-load = +10 Type II fibers: High-load = +22 Low-load = +18 |
| Vinogradova et al., 2013 | Young untrained men (n = 60) were allocated either to one of three high-load groups (80–85 % 1 RM) one moderate-load group (65–70% 1 RM) or one of two low-load groups (50% 1 RM). | Leg press | Training frequency was not presented; 8–10 weeks | Antibody method | Significant pre- to post-intervention increases in type II muscle fibers for the high-load groups. Significant pre to post-intervention increases in type I muscle fibers for the moderate-load and low-load groups. | Type I fibers: High-load = +9 High-load = +6 High-load = +6 Moderate-load = +18 Low-load = +18 Low-load = +18 Type II fibers: High-load = +23 High-load = +20 High-load = +33 Moderate-load = +6 Low-load = +8 Low-load = +6 |
*
Some studies presented only values for II muscle fibers without further typing to type IIa and IIx; RM, repetition maximum.