07-01-2020, 02:02 AM
(06-30-2020, 01:37 AM)Scott Stevenson Wrote: It certainly can be done, but I really had to MAKE time. I lost sleep to do so, but it was worth it all n' all.
I'm VERY interested in this. Do you have any pilot work published (e.g., a proceedings abstract or what have you)?...
I'm guessing you're familiar with this work:
1. Dudley GA, Harris RT, Duvoisin MR, Hather BM, and Buchanan P. Effect of voluntary vs. artificial activation on the relationship of muscle torque to speed. Journal of applied physiology 69: 2215-2221, 1990. http://www.ncbi.nlm.nih.gov/pubmed/2077019
2. Tesch PA, Dudley GA, Duvoisin MR, Hather BM, and Harris RT. Force and EMG signal patterns during repeated bouts of concentric or eccentric muscle actions. Acta Physiol Scand 138: 263-271, 1990.
3. Hather BM, Tesch PA, Buchanan P, and Dudley GA. Influence of eccentric actions on skeletal muscle adaptations to resistance training. Acta Physiol Scand 143: 177-185, 1991.
(And this more recent one: 1. Pain MTG, Young F, Kim J, and Forrester SE. The torque-velocity relationship in large human muscles: Maximum voluntary versus electrically stimulated behaviour. Journal of Biomechanics 46: 645-650, 2013. )
Gary Dudley was my mentor for my PhD.
I was all about maintenance when in school. Eating to gain would have put me in a carb coma (which is partly why I did and experimented so much with a low carb dieting).
Sounds like a solid plan and also one you can adjust depending on circumstances.
-S
Thanks for the replies Scott, eating enough to fuel training and recovery is somthing i do need to work on.
Yes i am very familiar with Dudley & Pain's work, trying to understand the unique neural activation strategies of eccentric contractions, and its implications, has been a large undertaking.
At the moment i only have the one conference proceeding (European college of sport science congress 2020), unfortunately this has been postponed until the end of the year due to the current pandemic.We will most likely not be presenting this data now as the university is restricting international travel as well as having updated the data since.
Here is the accepted abstract that we submitted:
Determining Concentric and Eccentric Force-Velocity Profiles During Squatting Using A Novel Motorised Isovelocity Device
Armstrong R, Baltzopoulos V, Langan-Evans C, Clark D, Jarvis J, Stewart C, & O’Brien T
Research Institute of Sport & Exercise Science, Liverpool John Moores University
INTRODUCTION:
Understanding the relationship between force & velocity (FV) is an integral part of resistance training prescription to optimise neuromuscular adaptation. Typically, as concentric (CON) velocity decreases, force production increases, and the force of eccentric (ECC) contractions exceeds that of concentric contractions. However, the majority of FV research focuses on single-joint movements, or on the CON portion of a multi-joint movement. No previous study has investigated the CON & ECC FV relationships in the squat movement, due to the challenge of applying high ECC loads and velocities safely and accurately. This study used a motor driven cable training system (Kineo, GLOBUS) that allows isovelocity squatting to construct the CON & ECC portion of the FV profile during a squatting exercise.
METHODS:
Following 2 familiarisation sessions performed at least 4 days prior to testing, 13 resistance-trained males (23 ± 3 years old, 1.6 ± 0.3 x BW squat) performed 3 repetitions of maximal effort isovelocity squats at 3 CON (0.75, 0.5, & 0.25 m/s) & 3 ECC velocities (-0.25, -0.5, & -0.75 m/s). The isovelocity phase of each movement was identified from the cable velocity plateau, and confirmed by 3D motion capture (Qualysis, 200 Hz). Peak vertical ground reaction force in the isovelocity phase from each trial was collected using 2 force plates (Kistler, 2000 Hz). Force data were low-pass filtered (6 Hz) and normalised to an estimated isometric force to construct the FV profile. A One-way ANOVA between velocity and peak force was performed, whilst a paired sample T-Test, with limits of agreement (LOA), were used to assess differences between target & actual cable velocity.
RESULTS:
Measured cable velocity had a small fixed bias (0.02 m/s) greater than the prescribed velocity (P<0.001, LOA=0.002:0.037). There was a significant effect of velocity on peak force (P=0.001). Peak CON force increased as CON velocity decreased. Peak ECC force at -0.5 & -0.75 m/s was greater than isometric force (21 & 25% respectively), but not at -0.25 m/s. However, normalised ECC force at all velocities was highly variable between individuals (SD = 0.37).
CONCLUSION:
This is the first study to investigate the CON & ECC FV profile in a squatting movement, with the Kineo appearing to be a viable method for controlling squat velocity. The CON FV profiles of all participants conformed to well established patterns. However, ECC FV profiles varied between individuals. On average, the group produced a peak ECC force ~25% greater than the greatest CON peak force. Though this ranged from -24% to +87%. Therefore, practitioners should be cautious of using a ‘one-size fits all’ approach when prescribing ECC overloads during squat training. Performing CON & ECC FV profiling has the potential to inform barbell squat load prescription to optimise neuromuscular adaptation. Further research should identify why ECC force production varied between individuals and which eccentric overloads maximise strength and hypertrophy.
We will be submitting the full paper to journals within the next month. Some things to note, we have since increased our population to 15 and changed the data analysis techniques. Which has lowered the peak eccentric forces to 10% greater than isometric force.
If you have any questions, please feel free to ask