Written Grant ProposaL: Caffeine and Accommodating Resistance Effect on The Rate of Force Development:A 12-Week Training Intervention
By: Abraham Campbell
Caffeine is one of the commonly most used performance aids in athletes. However, caffeine’s ergogenic effects on short-intense, strength, sprint, and power exercise remain unclear (Sökmen et al., 2008). Bazzucchi et al., (2011) demonstrated caffeine’s effectiveness on the rate of force development. The rate of force development is a measure of explosive-strength, it is the ability to produce force or torque during a rapid voluntary contraction from a resting state (Maffiuletti et al., 2016). RFD is important in both sport performance and for explosive-strength athletes (Maffiuletti et al., 2016). However, RFD (reduction) also has broader implications in association with functional daily living tasks in the elderly, in the context of rehabilitation interventions, and various pathologies (Buckthorpe & Roi., 2019; Maffiuletti et al., 2016).
Accommodating resistance (AR) is a training methodology whereas bands/or chains are attached to a weighted barbell and used during exercises such as the squat, deadlift, and bench press. These multi-joint exercises follow the ascending strength curve (Wallace et al., 2018). AR matches the ascending strength curve; where an individual can generate less force, resistance is reduced, and resistance is increased where an individual can produce greater force or torque. This methodology has shown efficacy in improvement in strength variables such as velocity, power, force, and RFD beyond conventional resistance training protocols (Wallace et al., 2018). However, to the knowledge of the author, no study has examined the combined synergistic effects of caffeine and AR on the rate of force development using sub-maximal weights at maximal speeds termed the Dynamic-Effort Method (Simmons, 2007). Therefore, it is hypothesized that combing the chemical (caffeine) and mechanical (AR training) stimuli will result in greater outcomes in the RFD and maximal/absolute strength (1RM) in the barbell squat, deadlift, and bench press. This will occur to a greater extent than using non-variable resistance training or in absence of caffeine supplementation. Additionally, it is hypothesized that a shift to right of the force-velocity curve will be the result amongst all maximal and submaximal intensities. Thus, producing greater force in less time.
Caffeine is infrequently studied in strength-based research and has been mostly examined using isometric strength protocols with conflicting results (Bazzucchi et al., 2011; Sökmen et al., 2008). However, Bazzucchi et al., (2011) demonstrated caffeine can improve neuromuscular performance during maximal dynamic isokinetic contractions. All participants improved the rate of force development in trials. Both centralized and peripheral neuromuscular factors are proposed to be contributors to the result. Commonly accepted peripheral factors pertain to caffeine’s interaction with; RyR1 ryanodine receptor subtype on skeletal muscle, increased release of Ca2+ from the sarcoplasmic reticulum, sensitization of Ca2+ to myofilaments and slow Ca2+ re-uptake (Bazzucchi et al., 2011). Allen et al., (2008) also propose that caffeine increases Na+/K+ ATPase activity but this remains unclear. Limited research on caffeine’s centralized effects on exercise performance have been determined. However, John et al., (2014) propose that adenosine reduces spontaneous and evoked potentials in the cerebral cortex, reducing neural firing rates caused by suppression of excitatory neurotransmitters (glutamine and histamine). Caffeine is an adenosine antagonistic that mitigates this suppression. Additionally, caffeine’s antagonistic effects on GABA (A) receptors mitigate neural inhibition and facilitate excitatory NT release (John et al., 2014). Maximal voluntary muscle activation is thought to be the result of the reduction of inhibition of the motor cortex and the greater ability to activate a motor unit pool after caffeine administration. Kalmar et al., (1999) propose that this may increase synaptic input from an upper motor neuron to a cell body of an alpha-motor neuron in the spinal cord may bring the MN closer to threshold enhancing maximal muscle activation.
“Speed-strength” or the “Dynamic Effort Method” (DE) (Simmons, 2007) are synonymous terms for improving the rate of force development using AR. Anderson et al., (2008) research using AR (chains or bands) demonstrated favorable results in strength and power as compared with traditional weight training in the barbell squat and bench press exercises. This study followed anecdotal protocols by Simmons (2007). Ghigiarelli et al., (2009) research on AR also showed improvements in strength, acceleration, and power-output in participants. Ghigiarelli et al., (2007) also cited improvements in the velocity during eccentric and concentric contractions. Research has shown similar improvements in strength variables using AR and barbell exercises. (Jones et al., 2014). However, limited studies have investigated the potential use of chain AR and RFD (Nijem et al., 2016). Researchers have proposed several mechanisms as to the determinants of AR training and its effect on velocity and RFD. Anderson et al., (2008) state greater acceleration using AR translates into greater average force development throughout the whole range of motion. Baker & Newton (2009) proposed greater velocities can be achieved using AR because of the post activation potentiation whereas various neuroreceptors sense existing force levels at the heavier portion of the ROM and activate the same number of motor units and rate of neural firing despite the disparity of loading between the top and bottom the ROM. This “surplus” of neural activation results in an improvement in barbell velocity is also in line with a more rapid stretch-shortening cycle.
The purpose of this proposed study is to investigate the synergistic effect of coupling caffeine and AR’s effect on the RFD. It is hypothesized that caffeine and AR will have a greater effect on RFD than caffeine or AR alone and a greater effect than non-variable resistance or in the absence of caffeine supplementation. Limited research has been completed on RFD and caffeine, or AR. Therefore, the primary aim is to investigate AR and Caffeine’s effect on RFD. Secondarily, to evaluate if RFD translates into maximal/absolute strength. Individuals will participate in a 12-week training intervention, divided into 4 randomized groups (n=10) (Caff + non-variable resistance), (Pla + NVR), (Caffe + AR), (Pla + AR). Participants (n=40) will be recruited from a “client roster” with males (n=20) and females (n=20) ages (n=20-40). Informed consent and ethical clearance will be obtained. Participants will be free from any neuromuscular and cardiovascular disease. All dietary (k/cal) and supplemental use with be kept at constant. Caffeine will be abstained from for a 24-hour period from each session. Caffeine or placebo will be administered in gelatin capsule 1 hour prior to exercise protocols. It will be administered in a blinded cyclically titration for 12 weeks (4 mg/kg, 5 mg/kg, 6mg/kg & 2mg/kg) per session each week (12) to prevent habituation and to a maximum dose as seen in the literature of 6 mg/kg (Bazzucchi et al., 2010). Baseline measures of barbell velocities (m/sec) and RFD will be recorded with 3 trials in each intensity of 1RM (40, 50, 60, 70, 80, 90, 100%) using a velocity and RFD measuring device (Tendo unit). This will occur after a dynamic “warm-up.” All groups will use the Dynamic Effort pendulum wave (Simmons, 2007). These three-week wave cycles will be repeated 3 times, three days of the week with 72 hours separating training sessions. Cycle loading intensities; Bench Press; (40% + 25%AR, 45%+25%AR, 50%+25%AR). Squat (50% + 25%AR, 55%+25% AR, 60%+25%AR) and the deadlift (60% + 25%AR, 65%+25% AR, 70%+25%AR). Participants will be encouraged to perform movement correctly, and as “explosively as possible.” Session duration will be 30 mins (3x per week). Rest periods will be 45 sec. (BP) and 60 sec. (SQ) and (DL). The NVR groups will use the same intensities of 1RM without AR (bar weight % 1RM + 25% AR). The weight chains will be suspended to the barbell with 1-2 links on the floor for stability. Every 4th week after 3-week cycle participants will complete a hypertrophy week consisting of 10 sets of 10 reps at 60% of 1RM (Month 1) 8 sets of 8 reps at 70% (Month 2) of 1RM and 6 sets of 6 reps at 80% 1RM (Month 3) for each exercise (Simmons, 2007). This is to negate any muscular hypertrophy due to the specificity of the training. After the cessation of 12 weeks, participants will abstain from exercise for 6 days before re-test on the 7th. Individuals will be tested at the following intensities of 1RM (52.5, 62.5, 72.5, 82.5, 92.5, 102.5%) with NVR. All participants will be administered caff 1 hour prior to trials (6 mg/kg) with three attempts at each intensity. Data will be analyzed between groups and within groups. It is expected that caffeine and AR group will show the greatest amount of improvement of barbell velocities and produce greater force in less time and increase their relative 1RM by 2.5%. Thus, demonstrating an improvement in RFD and RFD’s translation into greater absolute strength (1RM). The broader implication of these findings may change how exercise is prescribed particularly in rehabilitation, the elderly (fall prevention and balance) and in athletes. Many programs are focused on slow eccentric hypertrophy-based strength protocols. RFD is more important in the context of daily living tasks, performance and perhaps may minimize the age-related loss and function of motor-units (Piasecki et al., 2016).
The foremost potential problem of the study is participant adherence. The duration of the study and commitment may be an issue for many. However, personal training being a paid service perhaps enticing individuals with incentive for “3 months free training” maybe a strong motivating factor for consistent attendance. Additionally, it has been demonstrated that caffeine has fewer positive effects in females due to sex hormone differences (Temple et al., 2011). This maybe a confounding variable, if not addressed. Therefore, when analyzing the data, it would be important to conduct a comparison between genders in addition to the within groups and between groups comparison.
References
Allen, D. G., Lamb, G. D., & Westerblad, H. (2008). Impaired calcium release during fatigue. Journal of applied physiology (Bethesda, Md.: 1985),104(1), 296–305.https://doi.org/10.1152/japplphysiol.00908.2007
Anderson, C. E., Sforzo, G. A., & Sigg, J. A. (2008). The Effects of Combining Elastic and Free Weight Resistance on Strength and Power in Athletes. Journal of Strength and Conditioning Research, 22(2), 567–574. https://doi.org/10.1519/JSC.0b013e3181634d1e
Baker, D. G., & Newton, R. U. (2009). Effect of Kinetically Altering a Repetition via the Use of Chain Resistance on Velocity During the Bench Press. Journal of Strength and Conditioning Research, 23(7), 1941–1946. https://doi.org/10.1519/JSC.0b013e3181b3dd09
Bazzucchi, I., Felici, F., Montini, M., Figura, F., & Sacchetti, M. (2011). Caffeine improves neuromuscular function during maximal dynamic exercise. Muscle & Nerve, 43(6), 839–844. https://doi.org/10.1002/mus.21995
Buckthorpe, M., Roi, G. S. (2019). The time has come to incorporate a greater focus on rate of force development training in the sports injury rehabilitation process. Muscle Ligaments and Tendons Journal, 07(03), 435. https://doi.org/10.32098/mltj.03.2017.05
Ghigiarelli, J. J., Nagle, E. F., Gross, F. L., Robertson, R. J., Irrgang, J. J., & Myslinski, T. (2009). The Effects of a 7-Week Heavy Elastic Band and Weight Chain Program on Upper-Body Strength and Upper-Body Power in a Sample of Division 1-AA Football Players. Journal of Strength and Conditioning Research, 23(3), 756–764. https://doi.org/10.1519/JSC.0b013e3181a2b8a2
John, J., Kodama, T., & Siegel, J. M. (2014). Caffeine promotes glutamate and histamine release in the posterior hypothalamus. American journal of physiology. Regulatory, integrative and comparative physiology, 307(6), R704–R710. https://doi.org/10.1152/ajpregu.00114.2014
Jones, M. (2014). Effect of compensatory acceleration training in combination with accommodating resistance on upper body strength in collegiate athletes. Open Access Journal of Sports Medicine, 183. https://doi.org/10.2147/OAJSM.S65877
Kalmar, J. M., & Cafarelli, E. (1999). Effects of caffeine on neuromuscular function. Journal of Applied Physiology, 87(2), 801–808. https://doi.org/10.1152/jappl.1999.87.2.801
Maffiuletti, N. A., Aagaard, P., Blazevich, A. J., Folland, J., Tillin, N., & Duchateau, J. (2016). Rate of force development: Physiological and methodological considerations. European Journal of Applied Physiology, 116(6), 1091–1116. https://doi.org/10.1007/s00421-016-3346-6
Nijem, R. M., Coburn, J. W., Brown, L. E., Lynn, S. K., & Ciccone, A. B. (2016). Electromyographic and Force Plate Analysis of the Deadlift Performed With and Without Chains. Journal of Strength and Conditioning Research, 30(5), 1177–1182. https://doi.org/10.1519/JSC.0000000000001351
Piasecki, M., Ireland, A., Jones, D. A., & McPhee, J. S. (2016). Age-dependent motor unit remodelling in human limb muscles. Biogerontology, 17(3), 485–496. https://doi.org/10.1007/s10522-015-9627-3
Wallace, B. J., Bergstrom, H. C., & Butterfield, T. A. (2018). Muscular bases and mechanisms of variable resistance training efficacy. International Journal of Sports Science & Coaching, 13(6), 1177–1188. https://doi.org/10.1177/1747954118810240
Simmons, L. (2007). Westside Barbell Book of Methods. Westside Barbell.
Sökmen, B., Armstrong, L. E., Kraemer, W. J., Casa, D. J., Dias, J. C., Judelson, D. A., & Maresh, C. M. (2008). Caffeine Use in Sports: Considerations for the Athlete: Journal of Strength and Conditioning Research, 22(3), 978–986. https://doi.org/10.1519/JSC.0b013e3181660cec
Temple, J. L., & Ziegler, A. M. (2011). Gender Differences in Subjective and Physiological Responses to Caffeine and the Role of Steroid Hormones. Journal of caffeine research, 1(1), 41–48. https://doi.org/10.1089/jcr.2011.0005
