The TS was talking about 4-5 miles of running, this is hardly marathon type volumes and not enough to cause any significant decrease in muscle mass provided any resistance training is being done and protein intake is adaquate. Like I said in my original post, how do you explain NBA players getting far more aerobic work than that and still being muscular and being extremely explosive in their jumping ability?
Sure if you do huge volume of distance work you won't maintain a lot of muscle, but this is not because the body decreases CSA in order to increase capillary density, that's simply not how adapation works. It happens because a high volume of aerobic work is essentially catabolic and suppresses hormonal production so if you do no strength traning whatsoever to stimulate increased protein syntheis you'll end up with less muscle mass. But this doesn't mean the body gets rid of muscle tissue purposefully to increase capilary density. Practically speaking, the TS isn't going to lose a bunch of muscle from running 20-30 minutes a day.
The whole thing about aerobic training leading to you losing all your muscle mass has become totally overblown over the last few years. There are plenty of athletes with tremendous aerobic conditioning, including plenty in MMA, who also have a good amount of muscle. Verkhoshansky's programs for speed-strength sports always start with a block that aim to "increase peripheral vascular reactions and cardiac cavities" i.e. aerobic work, and maximum strength at the same time. Unless you are doing a large volume of aerobic work it is not going to cause you to lose all your muscle mass as many people seem to be saying these days.
As far as tendon elasticity, your original statement that plyometrics decrease tendon elasticity would mean that the tendons would actually contribute less elastic energy after plyometric training, is this really what you meant? How exactly are you defining elasticity? I can assure you that stiffer tendons DO NOT lead to an improvement in running economy. Plyometric training increases mechanical efficiency by improving the storage and utilization of elastic energy through the series elastic component (SEC), which is composed primarily of the tendonous complex and certain contractile components within the muscle itself.
One of the fundamental roles of plyometric traning and adaptations is the increase of the contribution of elastic energy this is how the contractile components of the muscle are able to do less work, because the elastic energy is contributing more to the total work being done. It is the combination of tissue deformation and mechanical stiffness that contributes to the elastic recoil of the stretch-shortening cycle. The greater change in length of the tendon means greater storage and utilization of elastic energy and less work done by the contractile components of the muscle.
"Less tendon stretch equals less work done by the muscle" is also oversimplistic and backwards. Because tendinous tissue is viscoelastic by nature the rate of stretch, total length of stretch, and the mechanical stiffness of the tissue all contribute to the elastic energy stored and released through SSC actions. The tissue deformation you are talking about actually leads to GREATER mechanical efficiency, not energy loss. The study posted below provides greater detail on this and contradicts your principle statement.
Notice that in the study the greatest mechanical efficiency occured when the change in tendon length was the greatest, not when it was the least as you have suggested. Tendon deformation and muscular work done are not linearly related as you stated either. A more compliant tendon, i.e. more elastic, means a greater change in length in the tendon relative to the fascicles, thus the two are actually inversely related.
CASE STUDY: IN VIVO ASSESSMENT OF MUSCLE‐TENDON UNIT KINETICS AND KINEMATICS IN RELATION TO MECHANICAL EFFICIENCY DURING JUMPING * (Biochemistry/Neuromuscular)
Andrea M. Dayne., Jeffrey M. McBride, Charles L. Dumke, N.Travis Triplett, James L. Nuzzo, and Michael A. Israetel Appalachian State University, Department of Health, Leisure & Exercise Science, Neuromuscular Laboratory, Boone, NC
PURPOSE: To determine the relationship between muscle‐tendon unit kinetics and kinematics and mechanical efficiency (ME) during various types of vertical jumping. ME has been reported to increase with increasing muscle pre‐activity and activity during the eccentric phase of a vertical jump. This increase in muscle activity is induced by increasing pre‐load
via a stretch‐shortening cycle (SSC) during a countermovement jump (CMJ) or drop jump (DJ). The observed increase in ME is thought to be a product of changes in muscle‐tendon unit kinetics and kinematics. While a number of investigations have examined ME or muscle‐tendon unit kinetics and kinematics during vertical jumping separately, none have investigated these two issues simultaneously.
METHODS: One recreationally weight‐trained male subject participated in one testing session. The subject performed 30 continuous repetitions of maximal static jumps (SJ), CMJs, and DJs from 125% of maximal CMJ height (125DJ). Muscle fascicle length change, tendon length change, patellar tendon force, and ground reaction forces were compared during eccentric and concentric phases of the jumps. ME was calculated from a combination of force‐time curves, displacement‐time curves and lactate‐corrected oxygen consumption values. Electromyography (EMG) of the vastus lateralis (VL) was also measured for each jump pattern in this investigation. Fascicle length of the VL was determined from real‐time ultrasonography. Patellar tendon force (PTF) and patellar length change (PTL) was determined utilizing an in vivo optic fiber technique.
RESULTS: ME was found to be 29.5% for SJ, 38.2% for CMJ, and 30.2% for 125DJ. Jump height was greatest in CMJ at 0.561m, followed by 0.480m (SJ) and 0.444m (125DJ). The greatest PTF and patellar tendon length change also occurred during the CMJ. PTF for
both the eccentric and concentric phases of each jump was 5640N and 5661N for SJ, 6838N and 7191 for CMJ, and 5243N and 5673N for 125DJ. The tendon continued to lengthen into the concentric phase of the vertical jump for all jump conditions. The greatest muscle fascicle length for each jump condition was 35.97cm SJ, 29.37cm for CMJ, and 20.93cm for 125DJ. Coincidentally, it was observed that PTL was maximized and fascicle length change was minimized as ME increased from SJ to CMJ. Conversely, it was found that during decreased ME (CMJ to DJ), tendon length change was minimized and fascicle length change maximized. Peak ground reaction forces in the eccentric and concentric phases were 1654N and 1934N for SJ, 1846N and 1974N for CMJ, and 2562N and 2552N for 125DJ. Average integrated EMG activity for the eccentric and concentric phases were 0.34mV and 1.94mV for SJ, 2.10mV and 2.30mV for CMJ, and 4.03mV and 4.29mV for 125DJ.
CONCLUSION: These findings suggest that increased ME may be related to maximal
tendon length change with minimal fascicle length change during SSC activities. This may be due to optimal usage of stored elastic energy in the tendon during the eccentric phase of the movement, thus resulting in increased performance.
PRACTICAL APPLICATION: Plyometric training that utilizes the SSC, such as CMJs, may lead to increased concentric muscle activity and increased ME. Therefore, including the SSC in training may assist in improving economy in running and jumping.
You are also missing that SEC stiffness/compliance plays a large role in phase of activation and timing of the concentric actions in SSC movements and that there will also be a difference between adaptations that lead to maximum economy and maximum power. Repetive effort plyometrics will lead to an improvement in maximum economy, single max effort shock method type work will lead to an improvement in maximum power.
"The major difference in the activation conditions for optimal power as opposed to efficiency are that the duty cycle is greater and the phase of activation is earlier for maximising power output. Increasing the relative compliance of the SEE(SEC) allows a muscle to activate earlier in the stretch
