Effects Of Drop-Set Training on High-velocity Lower Extremity Contraction

doi:10.21203/rs.3.rs-3934082/v1

Introduction: The ability of the lower limbs to undergo high-velocity contractions significantly impacts the capacity of athletes. However, not much is known about the effect of drop-set training (DST) on muscle contraction velocity. This study aimed to examine the impact of rapid drop set resistance training on high-velocity lower extremity contractions.

Methods: Sixteen teenagers were assigned to either traditional resistance training (TRT) or DST groups. The TRT group performed squats at 1.8 times their body weight, while the DST group performed squats at 1.8 then 1.3 times their body weight. Before and after training, knee muscle strength and body composition were measured using an isokinetic dynamometer and bioelectrical impedance tester.

Results: There were significant increases in fat-free mass, peak torque at 180°/s, and peak work in the right leg of the DST group. Peak torque, peak work, and average power increased significantly post-intervention butdid not differ significantly between the two groups.

Conclusion: Compared to constant resistance training, 1.8- and 1.3-times body weight drop training is more effective than constant resistance training in boosting muscle mass and strength during rapid contractions of the lower extremities. Furthermore, both TRT and DST effectively improve lower-extremity muscle strength at lower-speed contractions.

Biological sciences/Physiology

Biological sciences/Physiology/Bone quality and biomechanics

drop-set training

high-velocity contractions

lower extremities strength

traditional resistance training

muscle mass

Lower limb function is essential for athletes to excel in various sports^1–4. In particular, the ability of the lower limbs to contract rapidly significantly affects their maximum torque and power, directly impacting the athlete's capacity to run and jump⁵. For example, during sprint running, the lower limb muscles must rapidly contract to generate the kinetic energy necessary for quick movement^6,7. Similarly, when jumping, the lower limb muscles must contract quickly to achieve greater heights or longer jump distances^8,9. Therefore, enhancing the speed of contraction of the lower limb muscles in athletes is essential for success in several sports.

Numerous studies have investigated methods to improve muscle contraction capacity. Some of these methods include resistance training, eccentric training, kettlebell training, and ballistic training¹⁰. Among these approaches, resistance training is widely utilized to enhance muscle performance. Studies have explored the effects of resistance training on increasing the intensity of muscle function¹¹. Self-weighted or weighted squatting with increasing loads is a commonly used approach¹². This approach effectively enhances the maximal power of the lower limb muscles, especially the quadriceps, thereby enhancing athletic performance¹³. Nevertheless, a high external load causes the muscle to generate a greater impulse and time to counteract the load; hence, it cannot move at a high-speed⁵. Although there are various factors that can influence muscle contraction speed, such as initial stimulus, load, intention, and type of muscle action. In training, the method of changing the load is also used more frequently due to its simplicity and convenience¹⁴. The results revealed that all the tested training protocols employed smaller loads, resulting in an enhanced speed of movement; however, the improvement was not as significant when heavier loads were used. Ozaki et al.¹⁵ studied the effect of resistance training on rapid contraction strength in the low-load (LL) group at 30% 1-repetition maximum (RM) and the high-load (HL) group at 80% 1-RM. The results showed that muscular strength, cross-sectional area of muscle fibers, and muscular endurance measured by maximum repetitions at 30% 1-RM increased only in the LL group. Therefore, a novel form of resistance training is required to improve rapid muscle contraction under heavy loads effectively.

Research has shown that the neuromuscular system can adapt to external loads¹⁶. Under a high external load, the nervous system recruits a large number of muscle fibers, generating a significant impulse. If the load is reduced at this moment, the previously generated impulse accelerates the contraction speed of the muscle fibers, increasing the movement speed. Perez et al.¹⁷ observed that after a 6-week intervention for muscle hypertrophy, there was an increased percentage of myosin heavy-chain type IIa but a reduced proportion of myosin heavy-chain type I. Furthermore, Jones et al.¹⁸ observed that muscle fiber cross-section is closely related to muscle contractile function and improves maximal muscle strength. In the selection of loads, body weight load is a load that would be a good basis for selection of loads. Studies have shown that this indicator affects neuromuscular function¹⁹. Body weight load has also been used as a reference for intensity in resistance training²⁰. However, only a few studies have investigated the effects of drop-set training (DST) using body weight load on muscle contraction velocity. Therefore, this study aims to examine the impact of drop-set resistance training on the muscle mass of the lower limbs and the contraction velocity of the knee. Here, we compare the effects of DST with that of traditional resistance training (TRT) on lower limb muscle mass, knee flexion and extension moments, work, and power during isokinetic contraction at different velocities. This study hypothesized that DST would be more effective than consistent resistance training in enhancing lower limb muscle strength as well as improving knee flexion and extension moments, work, and power at high velocity.

Body Composition Evaluation

Analysis of body composition revealed significant differences in the fat-free mass (FFM) of the right leg (Table 1).

Table 1. Body Composition of Lower Extremities (N=16, Mean±SD)

Variables	TRT		DST
Variables	Pre	Post	Pre	Post
Weight (kg)	66.08±8.62	65.85±8.02	73.8±12.66	74.33±11.55
Skeletal Muscle Mass (kg)	33.04±4.95	32.45±4.27	35.66±5.10	35.93±4.39
Fat-Free Mass of Right Leg (kg)	9.29±1.25	9.28±1.22	9.83±0.89	10.00±0.83**^#
Fat-Free Mass of Left Leg (kg)	9.19±1.26	9.16±1.21	9.73±0.88	9.88±0.81

Note: TRT: Traditional resistance training, DST: Drop-set training, Pre: pre-intervention, Post: after-intervention, * Indicates a significant difference between times. ^#Indicates a significant difference between groups. (**:P<0.01,^#:P<0.05)

The interaction between time and intervention type has a significant effect on FFM [F (1, 7) =8.896, P=0.021, = 0.55]. Single effect test display. Time factor in the DST group has significant effects on FFM [F (1, 7) =12.810, P=0.009, = 0.65]. The FFM post-training significantly increased by 0.169 kg 95%(-0.280~-0.057kg) (p=0.009). After the intervention, the difference in FFM between the two groups was significantly different [F (1, 7) =, P=0.041, = 0.472]. The difference is 0.721kg 95% (-1.403 ~ -0.039kg) (P=0.041) (Figure 1).

Isokinetic Strength Test

Peak Torque of knee

Analysis of the lower extremity isokinetic peak torque revealed significant differences in the left leg (60°/s) flexors and extensors; right leg (180°/s) flexors and extensors; and left leg (180°/s) flexors and extensors (Table 2).

Table 2. Peak Torque of knee (N=16, Mean±SD)

Leg	Speed (deg/sec)	Statuses	TRT ( )		DST ( )
Leg	Speed (deg/sec)	Statuses	Pre	Post	Pre	Post
Left	60	Flexors	68.00±27.98	88.00±20.04**	79.43±21.08	85.57±20.44**
	60	Extensors	153.57±64.57	215.14±20.84**	171.38±39.43	196.75±56.31**
	180	Flexors	35.00±18.56	59.43±25.47*	45.71±28.41	62.29±15.21*
	180	Extensors	104.00±45.22	148.00±31.31**	106.00±32.02	136.88±37.51**
Right	60	Flexors	84.71±25.47	92.29±27.73	68.57±25.89	79.86±30.87
	60	Extensors	194.43±45.96	215.71±32.01	205.88±53.81	213.63±49.48
	180	Flexors	53.14±31.92	54.86±17.14	44.14±28.81	68.57±25.00^#
	180	Extensors	121.00±55.83	155.43±47.74***	128.13±39.94	153.63±35.02***

Note: TRT: Traditional resistance training, DST: Drop-set training, Pre: pre-intervention, Post: after-intervention, * Indicates a significant difference between times. ^#Indicates a significant difference between groups. (*:P<0.05, **:P<0.01, ***:P<0.001, ^#:P<0.05)The interaction between time and intervention type has a significant effect on the right leg (180°/s) flexors [F (1, 7) =7.873, P=0.026, = 0.53]. Single effect test display. Time factor in the DST group has significant effects on peak torque [F (1, 7) =12.415, P=0.01, = 0.64]. The peak torque post-training significantly increased by 24.429 95%(8.035~40.823 ) (p=0.01). (Figure 2).

The interaction between time and group did not have a significant but there was a significant effect of left leg (60°/s) flexors [F (1, 7) =16.59, P=0.005, = 0.70] post-training increased by 17.857 95%(7.49~28.224 ); left leg (60°/s) extensors [F (1, 7) =20.752, P=0.003, = 0.75] post-training increased by 43.473 95%(20.907~66.039 ); right leg (180°/s) extensors [F (1, 7) =44.899, P<0.001, = 0.87] post-training increased by 29.964 95%(19.39~40.539 ); left leg (180°/s) flexors [F (1, 7) =9.683, P=0.017, = 0.58] post-training increased by 23.001 95%(9.207~36.794 ) and left leg (180°/s) extensors [F (1, 7) =23.815, P=0.002, = 0.77] post-training increased by 37.438 95%(19.297~55.578 ). Regardless of intervention type, peak
torque was significantly higher post-intervention than pre-intervention (Figure 3).

Peak Work of Knee

Analysis of the lower extremity isokinetic peak work revealed significant differences in the left leg (60°/s) flexors and extensors; right leg (180°/s) flexors and extensors; and left leg (180°/s) flexors and extensors (Table 3).

Table 3. Peak Work of the knee (N=16, Mean±SD)

Leg	Speed (deg/sec)	Statuses	TRT ( )		DST ( )
			Pre	Post	Pre		Post
Left	60	Flexors	83.29±38.80	107.86±34.63**	94.43±27.98	105.43±27.85**
		Extensors	168.71±64.75	222.86±42.51**	197.63±42.61		223.13±73.69**
	180	Flexors	40.86±31.17	65.71±35.48*	47.00±33.02		66.00±19.62*
		Extensors	112.29±51.65	161.14±41.74**	117.25±41.20		152.25±48.49**
Right	60	Flexors	106.57±31.47	114.86±39.33	86.57±32.94		101.00±42.42
		Extensors	234.29±41.90	255.00±52.88	230.75±63.18		244.00±73.19
	180	Flexors	65.14±44.50	63.71±24.32	46.86±34.54		73.57±29.38^##
		Extensors	139.57±69.36	182.43±63.84***	141.13±51.62		171.50±52.17***

Note: TRT: Traditional resistance training, DST: Drop-set training, Pre: pre-intervention, Post: after-intervention, * Indicates a significant difference between times. ^#Indicates a significant difference between groups. (*:P<0.05, **:P<0.01, ***:P<0.001, ^##:P<0.01)

The interaction between time and intervention type has a significant effect on the right leg (180°/s) flexors [F (1, 7) =6.743, P=0.036, = 0.491]. Single effect test display. Time factor in the DST group has significant effects on peak work [F (1, 7) =14.521, P=0.007, = 0.68]. The peak torque post-training significantly increased by 26.75N 95%(10.151~43.349N) (p=0.007). (Figure 4).

The interaction between time and group did not have a significant but there was a significant effect of time on peak work of the left leg (60°/s) flexor [F (1, 7) =22.449, P=0.002, = 0.76] post-training increased by 23.625N 95%(12.382~34.868N), left leg (60°/s) extensors [F (1, 7) =15.083, P=0.006, = 0.68] post-training increased by 39.813N 95%(15.572~64.053N), right leg (180°/s) extensors [F(1, 7) =34.889, P<0.001, = 0.83] post-training increased by 36.563N 95%(21.925~51.2N), left leg (180°/s) flexors [F (1, 7) =6.911, P=0.034, = 0.5] post-training increased by 24.813N 95%(7.375~42.25N) and left leg (180°/s) extensors [F (1, 7) =22.084, P=0.002, = 0.76] post-training increased by 41.938N 95%(20.836~63.039N). Regardless of the intervention type, the best
work-per-repetition was significantly higher post-intervention than pre-intervention (Figure 5).

Average Power of Knee

Analysis of the lower extremity isokinetic average power revealed significant differences in the right leg (60°/s) flexors; left leg (60°/s) flexors, extensors, and deficit; right leg (180°/s) flexors and extensors; and left leg (180°/s) flexors and extensors (Table 4).

Table 4. Average Power of knee (N=16, Mean±SD)

Leg	Speed (deg/sec)	Statuses	TRT ( )		DST ( )
Leg	Speed (deg/sec)	Statuses	Pre	Post	Pre	Post
Left	60	Flexors	42.50±21.95	55.26±23.80***	44.70±16.63	53.40±14.10***
	60	Extensors	89.54±37.07	119.69±16.05**	102.56±21.79	119.44±34.73**
	180	Flexors	41.60±37.83	80.21±44.69	58.01±44.24	85.83±25.80
	180	Extensors	122.24±52.62	217.29±45.03***	137.89±39.43	202.89±60.91***
Right	60	Flexors	48.89±19.02	60.73±23.30***	41.26±20.50	52.54±20.97***
	60	Extensors	119.84±27.44	135.03±29.78**	109.36±34.77	127.33±34.82**
	180	Flexors	72.63±53.91	76.91±30.95	58.30±51.57	95.30±37.25
	180	Extensors	166.50±74.61	222.74±70.17***	170.06±74.68	224.91±48.01***

Note: TRT: Traditional resistance training, DST: Drop-set training, Pre: pre-intervention, Post: after-intervention, * Indicates a significant difference between times. (*:P<0.05, **:P<0.01, ***:P<0.001)

The interaction between time and group did not have a significant but there was a significant effect of time on average power of right leg (60°/s) flexors [F (1, 7) =60.029, P<0.001, = 0.9] post-training increased by 11.563W 95%(8.034~15.091W), right leg (60°/s) extensors [F (1, 7) =11.314, P=0.012, = 0.62] post-training increased by 16.5W 95%(4.901~28.099W) left leg (60°/s) flexors [F (1, 7) =32.193, P<0.001, = 0.82] post-training increased by 13.625W 95%(7.668~19.582W), left leg (60°/s) extensors [F (1, 7) =18.33, P=0.004, = 0.72] post-training increased by 23.438W 95%(10.493~36.382W), right leg (180°/s) extensors [F(1, 7) =34.131, P<0.001, = 0.83] post-training increased by 55.75W 95%(33.185~78.315W) and left leg (180°/s) extensors [F (1, 7) =35.847, P<0.001, = 0.84] post-training increased by 80.0W 95%(48.405~111.596W). Regardless of the intervention condition, the average power per repetition was significantly higher post-intervention than pre-intervention (Figure 6).

This study examined the effects of TST and DST on the muscle mass of the lower limbs, as well as the peak torque, peak work, and average power of the knee at various velocities. The results showed a significant increase in lower limb FFM in the DST group. We also found a significant increase in peak torque and peak work in the right leg at 180°/s. Furthermore, there was a significant increase in peak torque, peak work, mean power at 60°/s, and mean power at 180°/s compared to baseline, but there was no significant difference in these parameters between the DST and TST groups.

The reason for the difference between the right and left lower limbs may be that the participants were all right-handed. Some studies have also shown that the dominant limb produces a greater peak power than the non-dominant limb²¹. In our study, the DST group showed a more pronounced improvement in FFM in the right leg after 5 weeks of training. This is consistent with the report by Enes et al.²², who discovered that there was a significant increase in thigh muscle thickness during resistance exercise with DST. Temporary reduction in weight load to boost the number of repetitions could result in increased muscle fiber swelling and metabolic stress. These trigger changes in the pathways associated with ribosome and muscle protein synthesis, eventually contributing to increased muscle mass^23,24. Therefore, our study reaffirmed that DST was more efficient in enhancing muscle mass at certain loads.However, our findings were inconsistent with those of Ozaki et al.¹⁵, who used 80% 1-RM, followed by 30% 1-RM as gradually decreasing strengths. They found that training time had a significant effect on body composition among different groups. However, there was no significant difference between the DST and TRT groups. This discrepancy may be attributed to the limited duration of the training period²⁵. Ozaki et al.¹⁵ examined the impact of twice-weekly training for four and 8 weeks on FFM. No significant changes were observed after 4 weeks of training; however, after 8 weeks, a significant increase in FFM was observed.

Our results showed that the DST group achieved a higher peak torque and worked at 180°/s than the TRT group. This suggests that DST may be more effective in improving rapid muscular contractions. However, our results were inconsistent with those reported by Sawyer et al.²⁶ and Arazi et al.²⁷ Their results revealed that peak torque was improved by both constant-strength training and DST, with no significant difference between the two approaches^26,27. This discrepancy may be attributed to the selected strength load. In Sawyer and Arazi’s studies, they both chose 1-RM as a training load. In our study, we opted for 1.8- and 1.3-times bodyweight as the training loads, which is substantially lower than 1RM. Training with a smaller load enables the muscles to contract at higher speeds during exercise. This resulted in a more significant effect during the 180°/s isokinetic test. Previous studies have demonstrated that the peak torque produced by a joint during contraction can be affected by load intensity and training duration²⁸. In a study by Claflin et al., they found that type II muscle fibers possess a greater capacity for growth than type I muscle fibers and are mainly responsible for the strength of quick muscle contractions. Goto et al. discovered that DST was successful in rapidly raising growth hormone and blood lactate levels. Higher testosterone levels can stimulate type II motoneurons and possibly stimulate a higher contraction speed, which could be the reason it produces fast muscle contractions and improves muscle strength.At an extension speed of 60°/s, no differences were observed between the two groups. This could be attributed to the training protocol used. The DST may affect the quick contractions of type II muscles; however, it does not have any significant effect on the slower contractions of type I muscles. Therefore, we did not observe a significant difference in the kinetic parameters between the DST and TRT groups during slow knee contractions. These are consistent with the findings of Varović et al.²⁹, who also did not find a difference in muscle strength at 60°/s between the TRT and DST groups after an 8-week intervention.There was no discernible difference in the average power between the two groups at 60°/s and 180°/s. These results correspond with those of Fink et al.³⁰. Their study also found differences between DST and TRT in cross-sectional area (CSA) and 12RM, but not in maximum voluntary contraction (MVC) after 6 weeks of training.

Generally, the average power of a muscle indicates its potential explosive power. Muscle explosive force is mainly influenced by the CSA of muscle fibers and the ability to recruit motor units^31,32. Wernbom et al.³³ found that the relative contributions of motor unit recruitment and muscle hypertrophy to strength gains may change with training time. Neural adaptations may be more influential early in the 1–3-week period, whereas, after 4 weeks, an increase in explosive power is essential owing to changes in the muscle CSA. Based on this, Moritani et al.³⁴ found that the CSA of muscle fibers and the motor unit recruitment ability contributed almost equally to muscle strength after 3–5 weeks of training. This may explain why we did not observe a difference in explosive power between the two groups after the 5-week training. Shi et al.³⁵ found that after an intervention twice a week for 8 weeks, DST showed significant improvement in the squat jump (P = 0.014) compared with consistent resistance training.

Expansion of the lower limb muscles is associated with the amount of mechanical loading. Previous studies have examined the correlation between mechanical tension and muscle fiber growth. It was found that tension derived from resistance training causes chemical reactions in satellite cells³⁶. These satellite cells are beneficial because they contribute to the nuclei for the growth of myofibers, resulting in myofiber hypertrophy³⁷. Moreover, resistance training can cause muscle damage, leading to neutrophil aggregation and the release of growth factors that help repair the affected area. These growth factors promote the proliferation and differentiation of satellite cells and enhance muscle fiber hypertrophy^36,38. DST may be beneficial because of its ability to quickly reduce the load, causing a physiological response in type II muscle fibers. Previous studies demonstrated that type II muscle fibers are more susceptible to selective injury during exercise than type I muscle fibers³⁹. This is attributed to the structural distinctions between the two muscle fibers; type II muscle fibers have a narrower Z-line and are more susceptible to breaking during concentric contractions⁴⁰. Furthermore, in DST, the sudden decrease in load may have caused a reduction in the number of recruited muscle fibers, thereby increasing the risk of damage to the Type II muscle fibers. Damage to type II muscle fibers causes accelerated proliferation and hypertrophy, which, in turn, enhances the mechanical properties of rapid muscle contraction.

Despite the intricately designed study protocol, our study has a few limitations: 1) Our study participants underwent insufficient training time of 5 weeks. Extending the duration of the training intervention to 8 weeks would have provided a more comprehensive assessment of the effects of the training. 2) Indirect assessment of body composition using bioimpedance has an error of approximately 95% CI of mean between − 0.9664 and 0.5346 compared to the direct assessment of body composition using DEXA⁴¹. 3) Few indicators were monitored, and the hypothesized possible mechanisms were not demonstrated. Future experiments should monitor other indicators, such as growth hormone and blood lactate levels. 4) High repetition in resistant training may cause fatigue in subjects. In the future repetition of 3–5 times can be adopted.

Compared with TRT, DST is more effective in boosting muscle mass and strength during rapid contractions of the lower extremities. Furthermore, both TRT and DST improve lower-extremity muscle strength at lower-speed contractions. These findings are important in the selection of training exercises for athletes. More extensive studies on multiple joints are needed to provide a more comprehensive assessment of the effects of different types of training on muscle contraction.

Study Participants

This study recruited 16 male college students³⁰. The inclusion criteria were as follows: a) age between 18–30 years; b) at least 2 years of resistance training experience; c) minimum barbell squat relative strength of 1.8 times body mass; d) body mass index (BMI) < 26. The exclusion criteria were: no hamstring or other lower-extremity injuries recorded in the last 6 months. The participants were randomly assigned to either the TRT or DST groups (Table 5). All the participants were informed of the experimental protocol and provided informed consent. The sample size for this study was calculated a priori as follows: Effect size f=0.25, α err prob=0.05, power=0.8 (GPower 3.1, Dusseldorf, Germany). The required sample sizes were 16 for the TRT group and 8 for the DST group. Before conduction the experiment, the study was approved by the Ethics Committee of Shenzhen University (No. PN-202300124) and all study methods were performed in accordance with the relevant guidelines and regulations approved by the Research Ethics Committee. Informed consent was obtained from all participants prior to their participation in this study.

Table 5. Descriptions of participants (mean±SD).

Group	n	Age(year)	Mass (kg)	Height (cm)
TRT	8	19.8±1.4	66.1±8.6	174.8±6.3
DST	8	19.3±1.0	74.1±12.3	175.1±5.6

Note: TRT: Traditional resistance training. DST: Drop-set training

Procedure

During the strength training sessions, the two groups underwent different types of strength training programs. Each participant engaged in two strength training sessions per week for 5 weeks in total. Body composition evaluation and assessment of isokinetic muscle strength of knee flexion and extension at two speeds (60°/s and 180°/s) were conducted for each participant before and after the 5-week training period.

Body composition evaluation

Body composition was assessed in the morning using a multifrequency segmented bioelectrical impedance body composition tester (InBody 770, Biospace, USA). The participants were instructed not to eat or drink within 2 hours of waking up to ensure they fasted for 8–10 hours. The participants stood barefoot and upright on the base of the body composition tester, with the soles of their feet in complete contact with the oval electrodes. The electrodes were lowered naturally and separated from the body, and the participants were then asked to look straight ahead and remain quiet until the instrument completed the measurements. The test items included height, weight, muscle mass, fat-free mass, body composition, and other indicators.

Isokinetic strength test

The strength of the knee extensors and flexors was measured using an isokinetic dynamometer (Humac Norm Testing & Rehabilitation System; CSMI). Isokinetic dynamometers may be used to measure the force of muscle contraction at different angles by adjusting the strength that keeps the joint moving at a constant angular velocity. The isokinetic test consisted of strength measurements in both lower limbs during knee extension and flexion. The strength tests were performed at 60°/s and 180°/s, with five repetitions at each speed. Three sets of measurements were taken, and participants were given a 1-minute rest between each set. The participants then sat in the measurement chair while the torque of their knee joints aligned with the rotating axis of the dynamometer. Their thighs and upper body were tightly fixated using a strap and belt. Additionally, the ankle was fixated with a strap to isolate the muscle strength of the area of interest. This was done by adjusting the length of the lower leg and the adjustment axis with an adapter. After this, flexion and extension tests of the knee were performed. Parameters recorded include peak torque, peak work, and average power at each speed.

Strength training

Strength training sessions were conducted on Tuesday afternoons and weekends. Before beginning any training session, the subjects started with a 10-min general warm-up. Generally, this began with such as skips, high steps, lateral crossovers, and bodyweight squats to activate the joints. The TRT group performed 15 half-squats per set with a load of 1.8 times their body weight, completing a total of four sets. Conversely, the DST group first performed 10 half-squats with a load of 1.8 times their body weight, followed immediately by a load of 1.3 times their body weight with which they performed another 10 half-squats. These 20 squats comprised one set, and they completed four sets. Participants rested for 10 minutes between each set (Table 6). Half-squat training was performed under the protection of the equipment. All participants assumed a squatting position at a depth of 100° of knee flexion, with a rope secured laterally as a marker to ensure that the squat was consistent across all participants. Participants were encouraged to perform the half-squat as fast as they could. They were asked to avoid exercises designed to improve lower-extremity strength throughout the study duration.

Table 6. Exercises in each intervention group.

Group

Exercises（1-min rest between sets）

TRT

Barbell squats

（1.8 times self-weight:15reps×4sets）

DST

Barbell squats

(1.8 times self-weight:10reps+1.3 times self-weight:10reps)×4sets

Note: TRT: Traditional resistance training, DST: Drop-set training

Statistical analysis

SPSS version 27.0 (Chicago, IL, U.S.A.) was used for statistical analysis. The data were normally distributed, as evidenced by the Shapiro–Wilk test, and were expressed as mean and standard deviation (SD). Two-way repeated-measures ANOVA was conducted to evaluate the main and interacting effects. If a significant interaction was found, post-hoc analyses were performed for further investigation. The significance level was set at P < 0.05.

Author Contributions

Conceptualization, Zhiqiang Zhu.; Methodology, Zhiqiang Zhu., Mengkai Li.; Investigation, Lang Qin, Mengkai Li.; Writing—Original Draft Preparation, Lang Qin.; Writing—Review and Editing, Zhiqiang Zhu.; Supervision, Zhiqiang Zhu.; Project Administration, Zhiqiang Zhu.; Funding Acquisition, Zhiqiang Zhu. All authors have read and agreed to the published version of the manuscript.

Data Availability Statement

All data generated or analyzed during this study are included in this published article

Conflict of Interest

The authors declare that no commercial or financial relationships that could be construed as potential.

conflicts of interest were present during the research.

Kipp, K., Redden, J., Sabick, M. & Harris, C. Kinematic and kinetic synergies of the lower extremities during the pull in olympic weightlifting. J Appl Biomech 28, 271–278, doi:10.1123/jab.28.3.271 (2012).
Tschopp, M. & Brunner, F. [Diseases and overuse injuries of the lower extremities in long distance runners]. Z Rheumatol 76, 443–450, doi:10.1007/s00393-017-0276-6 (2017).
DiCesare, C. A. et al. Sport Specialization and Coordination Differences in Multisport Adolescent Female Basketball, Soccer, and Volleyball Athletes. J Athl Train 54, 1105–1114, doi:10.4085/1062-6050-407-18 (2019).
Zaras, N. et al. Rate of Force Development, Muscle Architecture, and Performance in Elite Weightlifters. Int J Sports Physiol Perform 16, 216–223, doi:10.1123/ijspp.2019-0974 (2021).
Tillin, N. A., Pain, M. T. G. & Folland, J. P. Contraction speed and type influences rapid utilisation of available muscle force: neural and contractile mechanisms. J Exp Biol 221, doi:10.1242/jeb.193367 (2018).
Bezodis, N. E., Willwacher, S. & Salo, A. I. T. The Biomechanics of the Track and Field Sprint Start: A Narrative Review. Sports Med 49, 1345–1364, doi:10.1007/s40279-019-01138-1 (2019).
Tottori, N. et al. Trunk and lower limb muscularity in sprinters: what are the specific muscles for superior sprint performance? BMC Res Notes 14, 74, doi:10.1186/s13104-021-05487-x (2021).
Koyama, K. & Yamauchi, J. Comparison of lower limb kinetics, kinematics and muscle activation during drop jumping under shod and barefoot conditions. J Biomech 69, 47–53, doi:10.1016/j.jbiomech.2018.01.011 (2018).
Bellinger, P. et al. Relationships between Lower Limb Muscle Characteristics and Force-Velocity Profiles Derived during Sprinting and Jumping. Med Sci Sports Exerc 53, 1400–1411, doi:10.1249/mss.0000000000002605 (2021).
Suchomel, T. J., Nimphius, S., Bellon, C. R. & Stone, M. H. The Importance of Muscular Strength: Training Considerations. Sports Med 48, 765–785, doi:10.1007/s40279-018-0862-z (2018).
Aube, D. et al. Progressive Resistance Training Volume: Effects on Muscle Thickness, Mass, and Strength Adaptations in Resistance-Trained Individuals. J Strength Cond Res 36, 600–607, doi:10.1519/jsc.0000000000003524 (2022).
Ogawa, M. et al. Effects of free weight and body mass-based resistance training on thigh muscle size, strength and intramuscular fat in healthy young and middle-aged individuals. Exp Physiol 108, 975–985, doi:10.1113/ep090655 (2023).
Kubo, K., Ikebukuro, T. & Yata, H. Effects of squat training with different depths on lower limb muscle volumes. Eur J Appl Physiol 119, 1933–1942, doi:10.1007/s00421-019-04181-y (2019).
Iversen, V. M., Mork, P. J., Vasseljen, O., Bergquist, R. & Fimland, M. S. Multiple-joint exercises using elastic resistance bands vs. conventional resistance-training equipment: A cross-over study. Eur J Sport Sci 17, 973–982, doi:10.1080/17461391.2017.1337229 (2017).
Ozaki, H. et al. Effects of drop sets with resistance training on increases in muscle CSA, strength, and endurance: a pilot study. J Sports Sci 36, 691–696, doi:10.1080/02640414.2017.1331042 (2018).
Markovic, G. & Mikulic, P. Neuro-musculoskeletal and performance adaptations to lower-extremity plyometric training. Sports Med 40, 859–895, doi:10.2165/11318370-000000000-00000 (2010).
Perez-Gomez, J. et al. Effects of weight lifting training combined with plyometric exercises on physical fitness, body composition, and knee extension velocity during kicking in football. Appl Physiol Nutr Metab 33, 501–510, doi:10.1139/h08-026 (2008).
Jones, E. J., Bishop, P. A., Woods, A. K. & Green, J. M. Cross-sectional area and muscular strength: a brief review. Sports Med 38, 987–994, doi:10.2165/00007256-200838120-00003 (2008).
Hwang, S., Jeon, H. S., Kwon, O. Y. & Yi, C. H. The effects of body weight on the soleus H-reflex modulation during standing. J Electromyogr Kinesiol 21, 445–449, doi:10.1016/j.jelekin.2010.11.002 (2011).
Li, S. S. W. et al. Effects of backpack and double pack loads on postural stability. Ergonomics 62, 537–547, doi:10.1080/00140139.2018.1552764 (2019).
Aoki, H. & Demura, S. Laterality of hand grip and elbow flexion power in right hand-dominant individuals. Int J Sports Physiol Perform 4, 355–366, doi:10.1123/ijspp.4.3.355 (2009).
Enes, A. et al. Rest-pause and drop-set training elicit similar strength and hypertrophy adaptations compared with traditional sets in resistance-trained males. Appl Physiol Nutr Metab 46, 1417–1424, doi:10.1139/apnm-2021-0278 (2021).
Figueiredo, V. C., de Salles, B. F. & Trajano, G. S. Volume for Muscle Hypertrophy and Health Outcomes: The Most Effective Variable in Resistance Training. Sports Med 48, 499–505, doi:10.1007/s40279-017-0793-0 (2018).
Hammarström, D. et al. Benefits of higher resistance-training volume are related to ribosome biogenesis. J Physiol 598, 543–565, doi:10.1113/jp278455 (2020).
Schoenfeld, B. J., Ogborn, D. & Krieger, J. W. Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis. J Sports Sci 35, 1073–1082, doi:10.1080/02640414.2016.1210197 (2017).
Sawyer, J., Higgins, P., Cacolice, P. A. & Doming, T. Bilateral back squat strength is increased during a 3-week undulating resistance training program with and without variable resistance in DIII collegiate football players. PeerJ 9, e12189, doi:10.7717/peerj.12189 (2021).
Arazi, H. et al. Comparable endocrine and neuromuscular adaptations to variable vs. constant gravity-dependent resistance training among young women. J Transl Med 18, 239, doi:10.1186/s12967-020-02411-y (2020).
Claflin, D. R. et al. Effects of high- and low-velocity resistance training on the contractile properties of skeletal muscle fibers from young and older humans. J Appl Physiol (1985) 111, 1021–1030, doi:10.1152/japplphysiol.01119.2010 (2011).
Varović, D., Žganjer, K., Vuk, S. & Schoenfeld, B. J. Drop-Set Training Elicits Differential Increases in Non-Uniform Hypertrophy of the Quadriceps in Leg Extension Exercise. Sports (Basel) 9, doi:10.3390/sports9090119 (2021).
Fink, J., Schoenfeld, B. J., Kikuchi, N. & Nakazato, K. Effects of drop set resistance training on acute stress indicators and long-term muscle hypertrophy and strength. J Sports Med Phys Fitness 58, 597–605, doi:10.23736/s0022-4707.17.06838-4 (2018).
Häkkinen, K., Alen, M., Kallinen, M., Newton, R. U. & Kraemer, W. J. Neuromuscular adaptation during prolonged strength training, detraining and re-strength-training in middle-aged and elderly people. Eur J Appl Physiol 83, 51–62, doi:10.1007/s004210000248 (2000).
Zamparo, P., Minetti, A. E. & di Prampero, P. E. Interplay among the changes of muscle strength, cross-sectional area and maximal explosive power: theory and facts. Eur J Appl Physiol 88, 193–202, doi:10.1007/s00421-002-0691-4 (2002).
Wernbom, M., Augustsson, J. & Thomeé, R. The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans. Sports Med 37, 225–264, doi:10.2165/00007256-200737030-00004 (2007).
Moritani, T. & deVries, H. A. Neural factors versus hypertrophy in the time course of muscle strength gain. Am J Phys Med 58, 115–130 (1979).
Shi, L. et al. Effects of Variable Resistance Training Within Complex Training on Neuromuscular Adaptations in Collegiate Basketball Players. J Hum Kinet 84, 174–183, doi:10.2478/hukin-2022-0094 (2022).
Toigo, M. & Boutellier, U. New fundamental resistance exercise determinants of molecular and cellular muscle adaptations. Eur J Appl Physiol 97, 643–663, doi:10.1007/s00421-006-0238-1 (2006).
Moss, F. P. & Leblond, C. P. Satellite cells as the source of nuclei in muscles of growing rats. Anat Rec 170, 421–435, doi:10.1002/ar.1091700405 (1971).
Vierck, J. et al. Satellite cell regulation following myotrauma caused by resistance exercise. Cell Biol Int 24, 263–272, doi:10.1006/cbir.2000.0499 (2000).
Fridén, J., Sjöström, M. & Ekblom, B. Myofibrillar damage following intense eccentric exercise in man. Int J Sports Med 4, 170–176, doi:10.1055/s-2008-1026030 (1983).
Fridén, J. & Lieber, R. L. Eccentric exercise-induced injuries to contractile and cytoskeletal muscle fibre components. Acta Physiol Scand 171, 321–326, doi:10.1046/j.1365-201x.2001.00834.x (2001).
Antonio, J. et al. Comparison of Dual-Energy X-ray Absorptiometry (DXA) Versus a Multi-Frequency Bioelectrical Impedance (InBody 770) Device for Body Composition Assessment after a 4-Week Hypoenergetic Diet. J Funct Morphol Kinesiol 4, doi:10.3390/jfmk4020023 (2019).

No competing interests reported.

Effects Of Drop-Set Training on High-velocity Lower Extremity Contraction

Status:

Version 1

Abstract

Figures

Introduction

Results

Discussion

Conclusions

Materials and Methods

Declarations

References

Additional Declarations

Status:

Version 1