Training

1. Training • Describe the differences between human exercise and animal models of muscle plasticity • Training-induced neural plasticity • Training strategies for modulating muscle recruitment

2. Training programs (cardio) • P90X/Insanity (12 weeks) • 30-60 min/day, continuous • Progressive (a little) • low load: no failure • 70-80% HRmax; 50-80% VO2max • Rotating muscle groups • HIIT (High Intensity Interval) • 30 min / day, continuous • 40-50% VO2max with 30-60s anaerobic intervals

3. Training programs (strength) • HIT (High Intensity) • 30-60 min / 2-3 day, short rests • 10-15 RM, recalibrated regularly, Consistent routine • HST (Hypertrophy specific) • 60-90 min/ 2-3 day, intervals • Progressive • Max-load (2x15, 12, 10, 8, 5-rep max) • Consistent routine, emphasis on form • Powerlift • 60-90 min/day, intervals • Progressive • High load (4x15, 12, 10, 8, 5-RM) • Rotating muscle groups , emphasis on completion

4. Training programs (research) • Endurance • 30-60 min/day • 60-80% VO2max • Consistent routine (usu. cycling/running) • Strength • 10-30 min /2-3 days • Single muscle group • 2-4 sets of 6-10 RM • 8-16 weeks

5. Human variability • Single greatest challenge to human research • Heterogenetic • Diet & activity variations • Drug/bioactive chemical variations • Sample size • n=5resolution ~2 S.D. • n=8 ~ 1.5 S.D. • N=12  ~1.2 S.D. Satellite cells pre/post training split by magnitude of hypertrophy (Petrella & al., 2007)

6. Recruitment • Voluntary • “Pacing” ie: projecting future activity requirement • Regulatory feedback • Recurrent/Renshaw inhibition • GTO/force dependent inhibition • Central fatigue • Skill • Involuntary • Intensity • Frequency • Synchrony Power-endurance curve, Morton & Hodgson, 1996

7. Recruitment during endurance ex • Pacing: activity increases at end • Temperature: central fatigue/stress reduces activity 15 °C 35 ° C 15 °C 35 ° C Activation restricted to ~30% MVC Tucker & al., 2004

8. Training specificity • Kanchisa & Miyashita (1983) • Isokinetic training atseveral speeds, 8 wk • Performance increasesonly near training speed

9. Training Specificity • Kitai & Sale (1989) • Isometric: 2x 10 “max” • 6 weeks • Strength gain only at training angle

10. Training Specificity • Aagard & al., 1996 • Soccer players • Isokinetic @8 RM, 24 RM • “Loaded-kick” 16RM @ 0-400 deg/s • High resistance improve isokinetic strength • No changes in kicking performance • “HST” vs “Power” training • Form over performance • Break in form may allow ‘testing’ of control pathways

11. Recruitment during controlled task Mechanical balance may limit the contribution of some muscles. Esp skilled motions fMRI of arm before & after maximal curl exercise (Adams & al., 1992) fMRI of calf before and after plantarflexion exercise (Yanagisaw & al., 2003)

12. Electrical stimulation • Animal • Cuff or hook electrodes on the nerve • Often anesthetized • Human • Surface electrodes • Awake subjects • Pain threshold fMRI of electrically stimulated quadriceps at tolerance limit ~50% activitation

13. Completeness of MVC • MVC: maximal voluntary contraction • Interpolated twitch • Add a single electrical pulse during MVC Tension rise due to synchronous, max activation Tension fall due to GTO, spindle feedback; antidromic collision Effect of an electrical pulse during voluntary activation (Belanger & McComas, 1981) Effect of an ‘extra’ impulse during an electrically evoked train (Belanger & McComas, 1981)

14. Completeness of MVC • Sensitive to posture • Sensitive to motion • Different among muscles • Confused by synergists Voluntary force (%MVC)

15. Endurance and interval • Burgomaster & al 2007 • 50 min continuous 60% VO2 cycling • 5x30s max anaerobic in 30 min • Equivalent metabolic gains • Similar signaling • PGC-1a • CS • etc

16. Long/slow contractions increase recruitment • MU fatigue reduces force capacity • Fatigued units replaced by new • Strategy for improving recruitment Garland & al., 1994 DeLuca & al., 1996

17. Sets and Reps • Berger (1962-1968) • 1-3 sets; 2-10 reps, 20 students/group • 12 weeks, max bench press 124±21 

18. Intensity-protein synthesis • Kumar & al, 2009 • 40-90% 1-RM • Reps set to match force*time • Protein synthesis 1-2 hr post • Can’t resolve anything • n=5 • Trend is consistentwith intuition

19. Sets and reps • Stuart Philips’ lab (2010-2012) • Vary sets and load (reps to failure) • Highest protein synthesis at lowest load • No difference in performance or hypertrophy mTOR/ERK siganling consistent with this Muscle Size Protein Synthesis 4x5 RM 4x14 @24 RM 4x24 @24 RM Mitchell & al., 2012 Burd & al., 2010

20. Detraining • Bickel & al., 2011 • 16 weeks Resistance training • 3x10-RM • 3/week • 16 weeks Detraining • No exercise • 1x10-RM, 1/week (1/9) • 3x10-RM, 1/week (1/3) • Age-dependent loss • 1/3 volume maintains young

21. Summary • Neural control is a big part of “strength” • Coordination of multiple muscles • Complete recruitment of individual muscles • Manipulating the nervous system is a big part of training • Practice to improve control • Fatigue to improve recruitment • Lessons from animal models are hard to translate • Forcehypertrophy • Chronic activityendurance