Abstract
Azevedo, APS, Mezeńcio, B, Valvassori, R, Anjos, FOM, Barbanti, VJ, Amadio, AC, and Serraño, JC. Usage of running drills in an interval training program: Implications related to biomechanical parameters of running. J Strength Cond Res 29(7): 1796–1802, 2015—The purpose of this study was to investigate the effects of running drills during an interval training program on biomechanical parameters of running. Thirty recreational runners, divided into 2 groups (control group and experimental group [EG]), were submitted to a 15-week interval training, but only EG performed running drills in the training. The test sessions were accomplished before and after intervention. Spatiotemporal and kinetic variables were analyzed at 2 speeds: maximum (Smax) and comfortable (Scomf). For moment effect, significant increases were observed for Scomf (8.9%) and Smax (10.7%) after training. Variables related to mechanical load were also higher after training for both speeds (LR1: 16.4% and Imp75: 7.8% at Scomf; LR1: 21.4% and Imp75: 8.1% at Smax). For training approach effect, higher value of Imp75 was observed in EG (10.1% at Scomf and 11.9% at Smax, without performance improvements). Also, EG presented higher values of Fy2 (6.7% at Scomf and 6.1% at Smax) and FT (13.3% at Scomf), variables related to the center of mass oscillation. As a conclusion, including running drills in a 15-week interval running training seems not to be an efficient procedure to improve parameters related to mechanical load and performance.
Key Words
ground reaction force, spatiotemporal variables, biomechanics, speed, mechanical load, performance
Introduction
Running has become an important aspect of practicing physical activities whether for aerobic conditioning or recreational sport (8,17). Moreover, running seems to be an important tool to train capacities such as strength, speed, endurance, and power (14,20).
Improvements in running technique and other parameters related to running training may be essential to refine mechanical load control and running performance (4,20,25). In practice, many training approaches have been used to induce changes in biomechanical parameters and benefit runners. Resistance training (24), speed training (6,14), functional training (18,22,23), and plyometric training (19) are some methods adopted to improve running performance. However, other training strategies seem to be more adopted in practice and deserve to be mentioned. The best examples of training to optimize running mechanics and improve running form are interval training.
Technical Drills and Biomechanics Rationale
Drill Descriptions and Cues
High Knees Drill
- Description: Runners lift their knees as high as possible while maintaining a quick turnover.
- Cues: “Lift your knees up to your chest, keep your feet close to the ground, and maintain a quick rhythm.”
A-Skips Drill
- Description: Runners perform a skipping motion with exaggerated knee lifts and arm swings.
- Cues: “Skip with high knees and strong arm swings, focus on driving your knees up and forward.”
Bounding Drill
- Description: Runners take long, powerful strides, emphasizing vertical leap and knee lift.
- Cues: “Jump as high as possible with each stride, land softly, and push off explosively.”
Butt Kicks Drill
- Description: Runners kick their heels back towards their glutes, focusing on a quick turnover.
- Cues: “Kick your heels back towards your glutes, keep your knees bent, and maintain a quick pace.”
Carioca Drill
- Description: Runners move laterally, crossing one leg over the other, while performing a side shuffle.
- Cues: “Cross your right leg over your left, then your left over your right, keep your knees bent, and maintain a quick pace.”
Coaching Points
- Emphasize the importance of maintaining proper form and technique during each drill.
- Encourage runners to focus on the specific cues for each drill to maximize the benefits.
- Gradually increase the intensity and duration of the drills as runners become more comfortable with the movements.
- Incorporate these drills into interval training sessions to enhance overall running performance and biomechanical efficiency.
Introduction
The addition of running drills in a running program is often questioned due to a lack of evidence supporting their effectiveness. Interval training and running drill training are two widespread approaches used to optimize running form. While interval training focuses on ability optimization, running drills aim to improve running technique. However, little is known about their influence on running mechanics, particularly when used together. Previous studies have characterized each training method alone, but their combined effects remain unclear. Therefore, the purpose of this study was to investigate the effects of a 15-week running drill usage in an interval training program on running biomechanical parameters. Changes in spatiotemporal and ground reaction force (GRF) parameters related to performance and mechanical load are expected when running drills are added to an interval training program.
Methods
Experimental Approach to the Problem
Recreational runners were recruited to test the efficacy of running drill usage in an interval training program. Participants were divided, in a balanced way, into a control group (CG) and an experimental group (EG). The treatment was the application of running drills in a running interval training program. Both groups performed a 15-week interval training; however, only the EG had the execution of running drills added to their interval running training. Participants were tested before and after intervention at 2 different speeds: maximum (Smax) and comfortable (Scomf). Spatiotemporal and kinetic variables were assessed to evaluate the effects of the intervention administered (interval training and running drills) on biomechanical parameters related to mechanical load and performance.
Subjects
Thirty recreational runners (12 men and 18 women; age, 24.28 ± 2.35 years; weight, 64.61 ± 9.67 kg; and height, 1.70 ± 0.09 m), with more than 6 months of running experience, were recruited. Participants were divided into 2 groups: CG (n = 15) and EG (n = 15). The criteria of exclusion were (a) the presence of musculoskeletal disorders in the 6 months preceding the study, (b) the presence of any medical impairment, and (c) previous experience in running drills or in any running technique training. The methodology and procedures used in this research were approved by the Ethics Committee from the University of São Paulo. All participants received a clear explanation of the study, including the risks and benefits of participation.
Running Drill Usage in Interval Running Training
Interval Training Details
Interval training consisted of about 6–16 running bouts executed in Smax, ranging between 100 and 600 m. The active interval consisted of jogging between 200 and 600 m in Scomf. Running drills added to interval training and executed only by the Experimental Group (EG) included:
- Skipping: Running forward with high knees (Figure 1A)
- Single-leg hop: Jumping upward with a single leg and landing in the same leg, leading leg with high knee (Figure 1B)
- Sprint: Running at maximal speed (Figure 1C)
- Anfersen: Running forward with high heels touching the buttocks (Figure 1D)
- Running bound: Running forward jumping as far as possible with each step, emphasizing high knee lift (Figure 1E)
Two trials of 50 m were performed by EG for each drill at every training session. The recovery period among trials and exercises was 20 seconds.
Data Analysis
MATLAB 2009b (MathWorks, Natick, MA) was used for signal processing. Specific mathematical routines were developed for this purpose. Ground Reaction Force (GRF) data were filtered with a 90 Hz low-pass Butterworth filter (fourth order) and normalized by the body weight of each subject. To evaluate the influence of running drills adopted in the interval training on mechanical load and performance, spatiotemporal and kinetic parameters were assessed. The parameters selected were:
- Comfortable speed (Scomf)
- Maximum speed (Smax)
- Stride length
- Stride frequency
- Contact time
- Time-of-flight (FT)
- Intensity of the first vertical ground reaction force (Fy1)
Illustration of Running Drills
Figure 1. Illustration of the running drills executed by the experimental group during intervention:
- A: Skipping
- B: Single-leg hop
- C: Sprint
- D: Anfersen
- E: Running bound
Kinetic and Spatiotemporal Variables
Table 1: Mean and SD values of kinetic and spatiotemporal variables, before and after intervention, at both velocities.
| Variables | Scomf | Smax |
|---|
| Fy1 (BW) | 1.53 ± 0.22 | 1.60 ± 0.26 |
| Fy2 (BW) | 2.29 ± 0.19 | 2.36 ± 0.23 |
| tFy1 (ms) | 31 ± 13 | 26 ± 5 |
| tFy2† (ms) | 117 ± 12 | 113 ± 13 |
| LR1*† (N$s21) | 53.06 ± 14.03 | 61.77 ± 15.84 |
| LR2 (N $s21) | 13.98 ± 4.07 | 15.33 ± 4.93 |
| Imp75*† (BW$s21) | 0.090 ± 0.011 | 0.097 ± 0.015 |
| Imp (BW $s21) | 0.374 ± 0.019 | 0.372 ± 0.017 |
| SL (m) | 0.88 ± 0.13 | 0.95 ± 0.15 |
| SF (Ss 21) | 2.74 ± 0.15 | 2.70 ± 0.20 |
| CT (ms) | 191 ± 24 | 189 ± 33 |
| FT (ms) | 173 ± 29 | 181 ± 47 |
*Significant difference between moments at the Scomf (p < 0.05).
†Significant difference between moments at the Smax (p < 0.05).
BW = body weight.
Kinetic and Spatiotemporal Variables Analysis
Key Parameters
The following parameters were analyzed to understand the biomechanics of running:
- Peak of Ground Reaction Force (GRF) (Fy1)
- Intensity of the Second Peak of GRF (Fy2)
- Time to First Peak (tFy1)
- Time to Second Peak (tFy2)
- Load Rate of the First Peak (LR1)
- Load Rate of the Second Peak (LR2)
- Total Impulse (Imp)
- Impulse of the First 75 Milliseconds (Imp75)
Mean and standard deviation (SD) of the load rate of the first peak of GRF (LR1) and impulse of the first 75 milliseconds (Imp75) at comfortable speed (Scomf) and maximum speed (Smax), pre-intervention (PRE) and post-intervention (POST).
- A significant difference between moments (p < 0.05) at Scomf
- *A significant difference between moments (p < 0.05) at Smax
Table 2: Kinetic and Spatiotemporal Variables
| Variables | Scomf | Smax |
|---|
| CG | EG | CG |
| Fy1 (BW) | 1.52 ± 0.17 | 1.61 ± 0.30 |
| Fy2*† (BW) | 2.25 ± 0.19 | 2.40 ± 0.21 |
| tFy1 (ms) | 28 ± 6 | 9 ± 13 |
| tFy2 (ms) | 118 ± 10 | 112 ± 14 |
| LR1 (N $s^-1) | 55.70 ± 14.10 | 59.13 ± 16.80 |
| LR2 (N $s^-1) | 14.14 ± 3.95 | 15.17 ± 5.07 |
| Imp75*† (BW$s^-1) | 0.089 ± 0.009 | 0.098 ± 0.015 |
| Imp (BW $s^-1) | 0.371 ± 0.017 | 0.375 ± 0.019 |
| SL (m) | 0.92 ± 0.14 | 0.91 ± 0.16 |
| SF (Ss^-1) | 2.76 ± 0.14 | 2.69 ± 0.20 |
| CT (ms) | 196 ± 23 | 185 ± 33 |
| FT* (ms) | 166 ± 31 | 188 ± 43 |
*Significant difference between groups at the Scomf (p < 0.05).
†Significant difference between groups at the Smax (p < 0.05).
BW = body weight.
This table provides a detailed comparison of kinetic and spatiotemporal variables for interval training without technical exercises (CG) and with technical exercises (EG) at both comfortable and maximum speeds.
Statistical Analyses
Data normality was verified by the Kolmogorov-Smirnov test, whereas the variance equality was tested by the Levene’s test. A two-way analysis of variance (moment and training approach) was performed for each speed (Smax and Scomf). When it was necessary, a post hoc Student-Newman-Keuls was used. The reliability of all variables was assessed by an intraclass correlation coefficient (3, 1) calculated for the mean value of each one of the 3 acquisitions of 10 seconds at each speed (0.77–0.89). The significance level adopted was p < 0.05. The statistical analysis was performed in the SigmaStat 3.1 (Systat) software.
Results
Significant differences were found between PRE and POST training moments in speeds analyzed (Scomf and Smax). Higher values (p < 0.05) were observed for both Scomf and Smax after training (Scomf POST: 9.76 ± 1.57 km/h; Smax POST: 13.77 ± 2.33 km/h) when compared with pretraining values (Scomf PRE: 8.96 ± 1.35 km/h; Smax PRE: 12.44 ± 2.44 km/h). Considering the intervention, no significant differences were found between CG and EG for any speed.
For spatiotemporal and kinetic variables, significant differences were found between PRE and POST training moments for both speeds (Table 1). The variables LR1 and Imp75 presented higher values (p < 0.05) after training period for Scomf and Smax (Figure 2), whereas tFy2 declined significantly (p < 0.05) after training for Smax.
Considering the training method, significant differences were observed between interval training only (CG) and interval training with running drills (EG) in Scomf and Smax (Table 2). Higher values of Fy2 and Imp75 were observed for EG in comparison with CG (p < 0.05) for Scomf (Figure 3). The variable FT was also higher for EG compared with CG (p < 0.05) for Scomf. In the same way, Fy2 and Imp75 were higher in EG when compared with CG for Smax (Figure 3).
Discussion
The aim of this study was to investigate the effects of 15 weeks of running drill usage in running interval training on spatiotemporal and kinetic parameters of running. To the best of our knowledge, this is the first study that has investigated the efficiency of running drills in an interval training to improve running mechanics.
The main finding of this study was that including running drills to a 15-week running interval training was not efficient to improve biomechanical parameters related to performance. Nevertheless, interval training was really effective to improve parameters related to performance. Moreover, parameters Figure 3. Mean and SD of impulse of the first 75 milliseconds (Imp75) and intensity of the second peak of GRF (Fy2) at comfortable speed (Scomf) and maximum speed (Smax) in experimental group (EG) and control group (CG). #A significant difference between training approaches (p < 0.05) at Scomf; *a significant difference between training approaches (p < 0.05) at Smax.
Running Drills and Interval Training
Introduction
Research related to mechanical load control seems to be impaired by the inclusion of running drills in interval training. As expected, the results do not support the inclusion of drills in a running interval training. Benefits expected from running drill training still remain a mere speculation.
After 15 weeks of interval training, Scomf and Smax increased significantly. However, this improvement occurred in both groups (CG and EG), which means that this performance improvement is a consequence of only interval training. Such evidence clearly points out the interval training as an efficient training strategy to improve running performance, corroborating to the literature (2,5,7,10,13).
Impact of Running Drills
The inclusion of running drills in the EG interval training did not bring any additional improvement in performance for this group. This result corroborates to the study by Sousa (21), who investigated the influence of a 6-week running drill training on the speed running and did not find differences for performance before and after intervention.
Mechanical Load Manipulation
According to the literature (11), running drills could be an interesting tool to manipulate the mechanical load in running. Johnson et al. (11) report that some technical exercises enable stimulating running technique while keeping a slower mechanical load. However, this advantage does not seem to reflect any benefit when technical exercises are performed with interval training as intervention.
Kinetic Variables
Important variables related to external forces (LR1 and Imp75) increased at both speeds (Scomf and Smax). Initially, such a change could be seen as a negative effect of proposed training. However, higher speeds were observed as a response to running training, as stated before. Considering kinetic variables are related to running speed (4,9,15), increased values were naturally expected for external force variables as a consequence of the greater performance observed after intervention. Nevertheless, higher values of FT (at Scomf), Imp75, and Fy2 (at Scomf and Smax) were observed for EG. As Imp75 is related to impact forces, results suggest that running drills could induce increments in mechanical load. As running drills in addition to interval training did not change comfortable and maximum speed, the increase of Imp75 was probably caused by changes in running technique. The Fy2 and FT are variables related to vertical oscillation of the gravity center (4). Thus, the higher Fy2 and FT for EG could represent a higher vertical oscillation of the gravity center as a response to running drill training. Such results also suggest a change in running technique (4) and lower running efficiency because of energy wastage (20).
Explanation of Differences
According to Kivi (12), running drills may have different movement characteristics when compared with running and would not simulate appropriately the running technique as expected. This evidence could help to explain differences observed between EG and CG.
Conclusion
Although changes in GRF and FT have been observed, our study did not find additional benefits from incorporating running drills into interval training programs.
