The Impact of AlphaPWR During In-Season Training
Heavy resistance training is a commonly employed strategy to enhance physical attributes due to the strong association between muscle strength and general sport skills such as sprinting, jumping and changing of direction. A common approach by trainers is to implement standardized percentage-based training (PBT), where the determination of set intensity often involves a direct 1-RM assessment, where a percent-based load is derived from a previous 1-RM lifted by the athlete. However, PBT may not accurately reflect the current maximal strength level of the athlete, as strength levels can fluctuate due to factors such as strength improvements over time or training-induced fatigue, especially during the competitive season. Additionally, daily stressors such as sleep, nutrition and illness can affect an athlete's readiness, and therefore cause acute changes in performance.
Technological progress has enabled the use of objective autoregulation methods for measuring exercise intensity, fatigue and volume. One of these methods is velocity-based resistance training (VBT). VBT uses the principle that there exists a linear relationship between movement velocity and %1RM, meaning that heavier loads cannot be lifted as fast as lighter load. Additionally, when an exercise is performed with maximal effort and fatigue sets in, movement velocity decreases. Intra-set velocity loss has a strong correlation with mechanical, perceptual and metabolic markers of fatigue, as well as with the relative number of repetitions completed in a set compared with the maximum achievable. Velocity loss can be used as an indicator of fatigue during resistance training and can also be used to regulate proximity to failure with reasonable precision.
Several studies have investigated the impact of different velocity loss thresholds on athletic performance. However, only a small number of these studies have been conducted on athletes, and none have been conducted during the in-season period when athletes have a high total volume of training and competitive games in addition to other physical training sessions. Therefore, we conducted a research project with the aim of comparing the effects of two resistance training programs on muscle strength, muscle size, maximal power, sprint and jumping abilities on in-season athletes, where each program differed only in degree of velocity loss in each set of the back squat exercise (20% versus 40% velocity loss). The back squat training was performed on the Alphatek PWR platform, and this blog post will cover this study’s methods, results, and also practical implications from performing VBT on the Alphatek PWR platform.
Methods
The participants in the study stemmed from two ice hockey teams. One being a male junior elite team (n=21), and the other being a female elite team (n=22), both teams playing in the highest national division. The intervention period was set to last 8 weeks, with 2 weekly intervention workouts, separated by at least 48 hours. Notably, the study was conducted in-season for the athletes, who had an average of 2 matches per week during the study intervention, as well as 4-5 weekly on-ice hockey training sessions. The participants underwent multiple pre- and post-tests, to assess potential effects from the training program. However, it is important to note that the intervention for the female group was prematurely terminated after only five weeks, and they subsequently underwent post-test measurements. The tests carried out were:
1-RM back squat test, to assess maximal strength.
Ultrasound of two muscles in the quadriceps (rectus femoris and vastus lateralis), to assess muscle thickness.
Keiser leg press test, to assess maximal power and force in the lower limbs.
30-meter sprint test on and off ice with 10-meter split time, to assess sprint performance
Countermovement jump (CMJ), to assess vertical jump abilities.
Training intervention
A randomized controlled experiment was conducted to investigate the effects of different velocity loss thresholds on back squat training. Participants were allocated to either the VL20 or VL40 group, stratified based on their back squat 1RM at baseline. The VL20 group performed their sets until they experienced a 20% decrease in velocity between their fastest and slowest repetitions within each set. Conversely, the VL40 group concluded their sets upon reaching a 40% decrease in velocity between their fastest and slowest repetitions. Notably, the variation in velocity loss was the sole distinction in load and intensity between the two groups.
The participants performed 6 weekly back squat sets, distributed on two separate workouts. All the back squat training were performed on the Alphatek PWR. The platform is very convenient and user friendly for all users and requires little to no learning. The screen in front of the platform displays plenty of objective feedback such as, movement velocity, velocity loss, maximal power, squat depth etc. For this particular group of athletes, we wanted them to focus on the maximal velocity achieved in every repetition and try to push this as high as possible. When the athletes reached their predetermined velocity loss (either 20% or 40%), the screen turned red, which terminated the set.
Table 1: Back squat training regime
Session 1 | Session 2 | Session 3 | Session 4 |
3 sets at 80% 1RM | 3 sets at 70% 1RM | 3 sets at 80% 1RM | 3 sets at 70% 1RM |
Session 5 | Session 6 | Session 7 | Session 8 |
3 sets at 80% 1RM | 3 sets at 70% 1RM | 3 sets at 80% 1RM + 2.5kg | 3 sets at 70% 1RM + 2.5kg |
Session 9 | Session 10 | Session 11 | Session 12 |
2 sets at 80% + 2.5kg | 2 sets at 70% + 2.5kg | 3 sets at 80% + 2.5kg | 3 sets at 80% + 2.5kg |
Session 13 | Session 14 | Session 15 | Session 16 |
3 sets at 80% + 5kg | 3 sets at 70% + 5kg | 3 sets at 80% + 5kg | 3 sets at 70% + 5kg |
Abbreviations: Sets: The total number of sets performed in the back squat exercise per workout. %1RM: Percentage of baseline one repetition maximum in back squat. The weight was increased with 2.5kg from session 6 to 7. This new load was kept from session 7 to 12, and then it was again increased with 2.5kg again from session 12 to 13.
Results
Prior to the research, we formulated hypotheses regarding the effects of different velocity loss thresholds on various outcomes. We anticipated that the group training to 40% velocity loss would exhibit greater muscle size development due to the established dose-response relationship between training volume and muscle hypertrophy. Conversely, based on previous research, we speculated that the group training to 20% velocity loss would demonstrate superior improvements in strength, power, sprinting, and jumping abilities. However, considering the participants' high initial strength levels and the demanding in-season training load, we were uncertain about the potential for positive changes from pre to post-test.
Muscle strength
Regarding the muscle strength variable, all groups exhibited substantial improvements in their back squat 1-RM scores (figure 1 and table 2-3). Notably, the female participants in the 40% velocity loss group achieved an impressive increase of nearly 13% within a five-week timeframe. Similarly, the male participants in the 40% velocity loss group experienced an approximate 10% improvement over the course of eight weeks. These findings suggest that training with a higher velocity loss, which leads to increased volume and a greater degree of fatigue, may be more effective in promoting additional strength gains, particularly for athletes who are already highly trained and in-season. Furthermore, the results obtained from the maximal force assessments conducted using the Keiser leg press further support the potential benefits of training until 40% velocity loss for eliciting or maintaining strength gains.
Mean group changes (with individual scatter plot) over the course of an 8-week VBT-intervention, from pre-test to post-test. Abbreviations: VL20 = Men training until 20% velocity loss. VL40 = Men training until 40% velocity loss. 1RM = one repetition maximum. Fmax = Theoretical maximum force * = Significant change from pre-test to post-test. ** = Significant change between groups at post-test (VL20 vs VL40)
Table 2: Overview of back squat 1-RM
Group | n | Pre (kg) | Post (kg) | Change (kg) | Change (%) |
VL20W | 6 | 84.4 | 92.5 | 8.1 | 9.6* |
VL40W | 7 | 81.0 | 91.3 | 10.3 | 12.8* |
VL20M | 8 | 131.6 | 138.2 | 6.6 | 5.0 |
VL40M | 7 | 127.9 | 140.4 | 12.5 | 9.8* |
Abbreviations: VL20W = Woman training until 20% velocity loss. VL40W = Woman training until 40% velocity loss. VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. Kg = kilogram * = Significant change from pre-test to post-test.
Table 3: Overview of maximal force derived from Keiser leg press
Group | n | Pre (N) | Post (N) | Change (N) | Change (%) |
VL20M | 8 | 357.9 | 349.6 | -7.7 | -2.2 |
VL40M | 7 | 328.7 | 242.9 | 14.2 | 4.3* |
Abbreviations: VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. N = Newton. * = Significant change from pre-test to post-test.
Power and sprint
When looking at the results from the leg press maximal power test (table 4), we see that the VL40M group had a significant increase from pre-to-post test compared to the VL20M group. Both groups also showed impressive results in the on-ice sprint test (figure 2 and table 5). However, the VL40M group showed the best percentage increase in both 10- and 30-meter sprint time, which aligns with the increases in muscle strength and power.
Mean group changes (with individual scatter plot) over the course of an 8-week VBT-intervention, from pre-test to post-test. Abbreviations: VL20 = Men training until 20% velocity loss. VL40 = Men training until 40% velocity loss. Negative values indicate a reduction in time.
* = Significant change from pre-test to post-test.
Table 4: Overview of maximal power derived from keiser leg press.
Group | n | Pre (W) | Post (W) | Change (W) | Change (%) |
VL20M | 8 | 2648 | 2648 | 0.0 | 0.0 |
VL40M | 7 | 2342 | 2449 | 107 | 4.5* |
Abbreviations: VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. w = Watt * = Significant change from pre-test to post-test.
Table 5: Overview of 10m split time on ice
Group | n | Pre 10m on (s) | Post 10m on (s) | Change (s) | Change (%) |
VL20M | 8 | 1.93 | 1.85 | 0.08 | -4.2 |
VL40M | 7 | 1.92 | 1.83 | 0.09 | -4.7* |
Abbreviations: VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. s = seconds * = Significant change from pre-test to post-test.
Table 6: Overview of 30m on-ice sprint times
Group | n | Pre 30m on (s) | Post 30m on (s) | Change (s) | Change (%) |
VL20M | 8 | 4.38 | 4.33 | 0.05 | -1.1 |
VL40M | 7 | 4.43 | 4.3 | 0.13 | -2.9* |
Abbreviations: VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. s = seconds * = Significant change from pre-test to post-test.
Muscle size
Ultrasound imaging was utilized to measure the muscle thickness of the vastus lateralis and rectus femoris (Table 6). Consistently, the 40% velocity loss groups demonstrated superior performance compared to the 20% velocity loss groups, exhibiting greater increases in muscle thickness for both muscles. While the patterns observed in muscle strength and power may not fully align with those seen in muscle thickness, the findings suggest that training until a 40% velocity loss may be more advantageous for promoting muscle gains in highly trained athletes during their competitive season.
Table 7: Overview of muscle thickness vastus lateralis
Group | n | Pre vastus lateralis (mm) | Post vastus lateralis (mm) | Change (mm) | Change (%) |
VL20W | 6 | 21.2 | 21.5 | 0.3 | 1.4 |
VL40W | 7 | 23.0 | 24.1 | 1.1 | 4.8* |
VL20M | 8 | 30.1 | 30.7 | 0.6 | 2.0* |
VL40M | 7 | 29.6 | 30.4 | 0.8 | 2.7 |
Abbreviations: VL20W = Woman training until 20% velocity loss. VL40W = Woman training until 40% velocity loss. VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. mm = millimetre * = Significant change from pre-test to post-test.
Table 8: Overview of muscle thickness rectus femoris
Group | n | Pre rectus femoris (mm) | Postrectus femoris (mm) | Change (mm) | Change (%) |
VL20W | 6 | 19.3 | 18.6 | -0.7 | -3.6* |
VL40W | 7 | 19.8 | 20.4 | 0.6 | 3.0 |
VL20M | 8 | 27.0 | 26.7 | -0.3 | -1.1 |
VL40M | 7 | 24.1 | 24.2 | 0.1 | 0.4 |
Abbreviations: VL20W = Woman training until 20% velocity loss. VL40W = Woman training until 40% velocity loss. VL20M = Men training until 20% velocity loss. VL40M = Men training until 40% velocity loss. n = number of participants. mm = millimetre * = Significant change from pre-test to post-test.
Practical implications
First and foremost, this study provides compelling evidence that in-season strength training on the Alphatek PWR platform yields significant and unexpected results. Both the female and male athletes demonstrated a remarkable increase in back squat 1RM of approximately 13% and 10% respectively. Such substantial gains are highly uncommon, particularly considering their already elevated strength levels and the demanding nature of the in-season period.
The objective of this study was to compare the effects of training to 20% and 40% velocity loss in the back squat exercise on various neuromuscular adaptations. Surprisingly, our findings diverged from our initial speculations and previous research, as the group training to 40% velocity loss exhibited superior outcomes in terms of muscle strength, maximal power, and sprint performance. These results may be attributed to the higher training volume naturally achieved when training to 40% velocity loss, leading to more repetitions and increased overall workload.
An important factor contributing to our success is the objective feedback provided to the athletes during training on the Alphatek PWR platform. The athletes received immediate feedback after each repetition and set, which is well-known to enhance motivation, movement velocity, and training quality in strength training. Our competitive athletes found the feedback displayed on the screen in front of them valuable for comparing their performance with both their peers and their own previous sets. The user-friendly nature of the platform, with a focus on achieving high concentric velocity and clear visual indicators, made it effortless to use. Within a few weeks, the athletes became highly self-driven.
In conclusion, we firmly believe that training on the Alphatek PWR platform provides significant benefits for athletes seeking to enhance their performance and elevate their strength training to new heights. The results obtained in this study speak for themselves, and the athletes thoroughly enjoyed this innovative approach to strength training, particularly due to the comprehensive feedback they received, enabling easy self-comparison and progress tracking. The platform's user-friendly design allows athletes to simply step onto it and begin their workout, with a wealth of variables and feedback provided after every repetition and set. We are delighted to have had the opportunity to conduct research using the Alphatek PWR platform and eagerly anticipate future experiments utilizing this technology. We are confident that this training tool will revolutionize strength training in the coming decades.
This article is written by:
As a grand finale to this blog, we encourage you all to tune into our podcast, "Trening med Teknologi". We were fortunate to have Sander and Nicholas as our guests, who discussed the study they conducted on the Stavanger Oilers hockey team. This conversation is packed with fascinating insights about training, technology, and the road to peak athletic performance.
You can listen to the podcast here: Trening med Teknologi - Episode 1
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