A bunch of Scientific research from ACSM conference

Last week was the big American College of Sports Medicine annual meeting.  I wasn’t in attendance as I was at the Prefontaine classic. So instead I had the pleasure of browsing through the 3,500+ abstracts that were presented at the conference.  There were a lot of interesting studies to pop up, so I figured I’d share my highlights of the abstracts.  In the coming weeks, I’ll go through some of the more intriguing studies to come out and give their real life impacts.

(Some are more in depth than others because I was taking hand written notes as my computer broke…So, if you want to search the abstracts, I’ve included the authors when I remembered.  Also, remember that experimental procedure and subjects matter.  So just because I say X did Y, it doesn’t apply to everyone..)

My comments on the studies will be in blue.

(Full abstracts can be seen here: http://acsmannualmeeting.org/wp-content/uploads/2012/04/12AMFinalProgramCombined.pdf )

Exercise Induced Arterial Hypoxemia:

·         -The higher the VO2max, the more likely for oxygen saturation to be less than 91% at sea level.  71% of well trained reached low oxygen saturation levels (Chapman)

·         -Mechanical ventilator constraints are a contributor

·         -Faster runners- pulmonary diffusing capacity of nitric oxide is limited

·         -Aveolar-capillary membrane conductance is a limiter (Lavin et al.)

Impact: Limiters and physiology change as you deal with people futher outside the norm.  For highly trained athletes, O2 saturation drops might play a role.  This might be the reason various interventions in terms of respiratory training are successful.  It depends on the population you are addressing.  It’s simple to test if an athlete has EIAH.  Simply buy a pulse oximiter for $60 and then test during a really hard workout.

Inspiratory Muscle Training/Diaphragm:

Speaking of EIAH, there were a few interesting studies on inspiratory and expiratory training.

-"After IMT, highly-trained competitive cyclists demonstrate decreased whole-body VO2, and LM and RM deoxygenation during exercise with heavy inspiratory loading. These data suggest that IMT reduces respiratory muscle

demand and decreases oxygen extraction by the active muscles, which may reflect IMT-induced changes in respiratory and limb locomotor muscle oxygen delivery."

Electrical Activity of the Diaphragm in Trained Subjects During Progressive Cycling to Exhaustion Trials

Dan S. Karbing, Nicolai L. Mifsud, René M. Jørgensen,

CON CLUSIONS : Results showed poor within subject agreement over time for EAdi. Possible causes include probe placement and subject variation over time. In contrast, trends in EAdi changes with workload were similar within subjects. In general, EAdi increased from WL of 40% to 55% and 70%. On average, a plateau at 85% WL was indicated in agreement with previous studies of EAdi, but individual subjects showed no clear pattern of changes in EAdi from 70 to 85% WL.

What I loved about this study is that it showed diaphragm activity was highly variable.  The diaphragm and breathing are starting to get attention once again in terms of limiting performance after going through a phase where it didn't really matter.

 Lactate:

-Negative effect on differentiation of human myoblasts

-regulates proliferation, apoptosis, and differentiation (Jung)

Myoglobin:

-Contrary to prior beliefs, myoglobin is not only in cytosol. Plays role in regulating mitochondria respiration

Fiber Type:

-muscle activation patterns can alter fiber type through six 1 gene. 

Essentially the fiber type can be “trained” based on its use.

Satellite cell: (SC are essential for the muscle repair and growth)

-Increases 4 days post but not 10 days after a bout of strength training

-Concurrent endurance blunted satellite cell proliferation.  (Thus why endurance training and strength training performed together can reduce hypertrophy)

Ultrasound:

-Ultrasound increases muscle cell proliferation in isolated muscle cell giving a potential investigative reason for ultrasound to work

Ibuprofen:
-Increase skeletal mass in older adults by decreasing IL-6.

Interestingly, in older adults, ibuprofen INCREASED hypertrophy.  According to the authors, it most likely does so by decreasing IL-6.  The interesting thing is this runs contrary to other research done in younger people.  There’s much to investigate on this but it could point to a different limiter in terms of hypertrophy depending on age (and likely related to hormonal differences

-"Consumption of 1,200 mg·d-1 of ibuprofen for 3d following an initial novel bout of eccentric contractions significantly diminished the well-established neuromuscular adaptation (repeated bout effect) that commonly occurs following injurious exercise. Athletes should use caution when utilizing NSAIDs to treat lower extremity muscle pain.

Once again, some more research showing that NSAIDs might block some nice adaptations or recovery.  Save it for when you really need it!

Whole body vibration

-Improved running economy in college distance runners in terms of both caloric unit cost and distance unit cost. (Ching-Feng Cheng)

-Improves vertical stiffness (Coglianese)

While it’s only a few studies, it’s interesting that WBV improved economy, and in some other studies power, in the short term.  It would be interesting to see what the long term studies would show.  For why it happens, as mentioned, another study showed an increase in vertical stiffness which may play a role in increasing RE.

Weight Loss:

·         Weight loss results in decrease in T to C ratio

Fatigue

·         Low frequency fatigue is caused by reduced SR Ca2+ release

·         CNS tolerates greater magnitude of peripheral fatigue when source of skeletal muscle afferent feedback is confined to small muscle mass (Rossman, Venturelli)

o    (One large feedback versus many diffuse signals- many fatigue signals-CNS shuts down stuff sooner)

·         Cognitive demand (math) increase muscle fatigability

·         Metabolite detecting markers decrease post exercise=down regulation of afferent signaling in order to reduce fatigue sensations (Van Haitsma)

Some very interesting studies coming out on fatigue and in particular on how fatigue is relayed. 

Signal pathways:

·         NCoR1- opposite effect of PGC-1a

·         mTOR

o    intervals before strength blunts mTOR

§  (Once again shows why timing matters when you do stuff)

o    Whey- 20g post resistance training= increased mTOR activation

·         A7integrin=upregulated in response to mechanical strain- regulates p70S6k signaling which increases fiber hypertrophy.

·         PGC1-a

o    Upregulated for up to 6hrs post exercise in novice

·         Sumo-1-

o    Triggered by oxidative stress/hypoxia- peaks 15-30min post exercise

·         Attenuated response of PGC1-a and MURF-1 after just 10 days of training (about 1/3 of the increase after 2^nd time trial) (Hinkley)

o    This one is interesting because it shows that training has to adapt to elicit further response of a signaling pathway.  The stress has to be manipulated.  Thus why you can’t just do the same thing over and over and get results.

Epigenetics:

-exercise alters DNA methylation- aerobic+ resistance altered more sites than RE only (6976 vs 970) and only 197 genes common in both (Radom-Aizik, Haddad)

I love epigenetics.  It’s one of my favorite side interests, so to see a study looking at epigenetic changes due to exercise is very interesting.  In  past studies, there’s been data to show that some epigenetic changes get passed down.  What would be interesting to know is how much exercise related epigenetic changes can get transferred to the next generation.  Additionally, what’s intriguing on this one is the number of sites modified in endurance+resistance versus resistance only.  AND that there wasn’t a huge overlap. 

Altitude:

-Time-trial performance is impaired to a greater degree in hypobaric compared to normobaric hypoxia at the same ambient PO2 equivalent to 4300 m despite similar cardiorespiratory responses.

This one is very interesting because it shows that Oxygen isn’t the only thing that matters.  Pressure seems to play a role too.  So altitude tents alone won’t do the entire job?

·         -Nitric Oxide/Nitrates decreases the effects of altitude.

o    Use when racing at altitude, or when needing better workout at altitude.

·         -Lower HRV- leads to parasympathetic withdrawal and increase in sympathetic activity (Rodriguez)

o    Shows that stress response at altitude changes and you have to consider it when training.

·         -Living high, training low= increase in cortisol.  AND increases muscular protein degradation/catabolism.

o    –Shows that when at simulated altitude, need to probably increase protein intake, and be aware of the increased stress response and likely decreased recovery from training.

I think the take away from the above studies is to think of altitude as a stressor, just like any other workout or new training stimulus.  I'd venture to guess that why a large majority of people who go to altitude and don't see positive adaptations, is because they "overtrained" at altitude because they didn't realize it was an additional stressor.

Training effect of altitude on breathing:

"CON CLUSIONS : Decreases in the oxygen cost of breathing accounts for

approximately one-quarter of the improvement in running economy in elite distance

runners after altitude training. The data suggests that the added ventilation with chronic

training at altitude acts as an additional training effect for the respiratory musculature,

which may contribute to altitude training-mediated performance improvements."

Heat:

-Heat preconditioning (30min hot bath) eliminates increase in IL-6 and CK following eccentric work (Wang)

Blood donation:

  -Donating blood causes temporary spike in NOS and EPO (500ml donated)

Muscle

-marathon training modifies muscle architecture (higher pennation angles and shorter fascicle lengths) (lateral gastroc more likely to change than vastus lateralis/

Power:

-in rats, peak power training decreased FTb fiber SDH (mitochondrial) activity. 

Intriguing because it shows the interplay and balance that is essential in finding that speed vs. endurance balance.  If you sway too much on one side you can mess up the balance.

Protein

-whey increases mRNA expression post resistance training

-L-arginine with resistance exercise blunts GH response

-Leucine=activator of protein synthesis proteins, HMB inhibits protein related to protein degradation (Wang)

-choc. Milk better at decreasing muscle damage then whey protein fix (Fornal)
Protein is becoming a bigger deal, even for endurance athletes.  And it not only matters that you take it in, but also when and how much. 

Biomechanics and Shoes:

-VFF improve RE after 2 week adaptation period in national level runners (Warne)
-De Paoli- Inexperienced barefoot more economical barefoot than when shod.
-Zero drop shoes change foot angle at touch down so its closer to barefoot (Bohne)
More interesting stuff on shoes and the barefoot trend.  What I like about the VFF and RE study is that they at least gave them an adaptation period instead of doing the stupid RE in shoes then right after in VFFs. 

Additionally, the zero drop shoe study shows what we've all been saying for a while.  Heel height plays a specific role in the angle of the foot at landing.

"Does Gait Retraining To Decrease Vertical Loads Reduce Bony Loads In Runners?"

Rebecca E. Fellin1,

:External and bony loads appeared to decrease post gait retraining.:"

-Increased hip strength resulted in decreased ROM for both pelvic drop and trunk rotation during the stance phase of running in collegiate athletes.

Biomechanics and Fatigue:

-Fuhr et al- found that "These results indicate that changes in mechanics occur throughout the simulated 10 km run and these changes are magnified as runner’s fatigue. Mechanical changes such as these may be compensatory in nature. Increased elbow flexion may have assisted propulsion by increasing the amount of lift acting on the body and ultimately increasing the individual’s total flight time. This, combined with increased knee flexion, seem to be key coping strategies to maintain pace with fatigue induced step frequency decreases.

 Cool study that shows what all of us track coaches see.  As Fatigue occurs (in this case over a 10k race) mechanics change.  The take away on this study is the changes in arm stroke to compensate for fatigue.  The question is can we delay this need to alter mechanics until we really need to.  And secondly, is there a preferred way to compensate for fatigue.  For example, many runners try to do the lift the knee thing when fatigued, which I'd say is incorrect.  Are there certain things to teach to go to when fatigued?  My advice has always been to focus on the arm swing.  Depending on the athlete, either increasing frequency or stroke range of motion could be helpful.  I think what way they go depends on what there "normal" mechanics are.  If they are an athlete who generally maximizes stride frequency then you probably aren't going to be able to compensate to keep frequency up and instead would have more luck in increasing stride length.  Or vise versa.

Muscle Damage:

Discussion: These results suggest that muscle damage induced by ECC increased

corticospinal excitability, which was seen at high stimulator output levels. This could

be attributed to increased EMG activities and force fluctuation during voluntary
contractions of damaged muscle.
Eccentric muscle damage changes EMG activity. 
 

Baseball:

-Using a heavy or light bat while warming up, shows a trend in decreasing bat swing velocity when swinging your regular bat. 

I love this study because it shows that once again something that baseball has been doing for a century is idiotic...(i.e. donuts on the bat in the on deck circle).  There are other studies that found the same thing.

Carbs:

Immediate Energy Signaling During Physical Activity

-Study by Grant, Turner, et al. showed that swishing around Carbs enhanced neural activation network.  It increased activity in the motor cortex and "regions involved in reward processing."

This explains why swishing around carbs and spitting them out seems to work.  Your body and brain is a wonderful thing.  It's pretty cool how feedback works.

Study on nutrition and efficiency:

"CON CLUSIONS : Significant differences in gross efficiency were obtained following alteration of nutritional intake in the 3-days preceding and during exercise. This suggests that nutritional intake should be carefully controlled and monitored to ensure the validity of gross efficiency measurements.

Core and RE:

RESU LTS : Right and left side bridge, flexor, and back extensor endurance times were significantly (p < .05) increased following training. Interestingly, despite increases in core endurance, a significant (p < .05) decrease in RE was observed.

 This study was interesting because it found an increase in core endurance, yet a decrease in economy...which is what all the core fanatics say is supposed to be improved.  This doesn't mean that core is bad, it just makes you ask the question of why economy was decreased...or it tells you the measurement of RE is kind of crap...

Caffeine:

-"Caffeine was ergogenic during leg, but not arm cycling and this effect may be attributable to preserved muscle activation in the KE."

Training in pollution:

-"The results show that regular exercise in urban environment with high traffic - related air pollution increases markers of respiratory and systemic inflammation. In line with our previous findings where the exercise-induced increase in BDNF does not occur with exercise in polluted air, this study shows no improvements in cognitive performances with training in polluted air."

In this study they looked at training in Brussels versus the country side.  Very interesting that training in city manipulates systemic inflammation.

Pregnancy:

Aerobic training improves mitochondrial function in human placenta by increasing mitochondrial respiratory complexes activity and decreasing H2O2 production. This intervention favors fetal oxygenation and substrate delivery and could

help protection on gestational disorders associated to impaired mitochondrial function.

This is not relevant at all to me...but it still is really interesting....yaaaa I dunno..

 Eccentric Training:

-"Following eccentric exercise, we observed an increase in blood flow and blood volume within the microvasculature of the gastrocnemius over 48 hours."

An increase in blood flow and volume might help explain why eccentric work seems to work so well.

Strains/muscle injury:

-"The data show that muscle strain injury causes morphological changes to the NMJs. Due to the short time course used here, changes in NMJ morphology among injured myofibers is likely not due to regeneration or a change in myofiber size. This focus toward the NMJ represents a paradigm shift from more prevalent myocentric perspectives on injury."

 

Neuroscience:

-"We observed that cardiorespiratory fitness levels play a role in the effects of exercise on activity in frontal and visual brain regions involved in food processing. These data appear to suggest that LF individuals have a greater suppressive

affect in brain regions that regulate appetite."

How cool is this?  Fit people can suppress that urge to eat much better than non fit.

Pacing:

-Foster- accumulated RPE. Instead of just doing a session RPE, Foster et al. did accumulated RPE over a race and found that 50% effort completed at 60% of the distance. So the last 40% of the race takes 50% of the effort.

Accumulated RPE is a cool, simple way to look into effort over race distance.  It makes intuitive sense that more of the effort is divied out during the last part of the race.

 
VO2 over 800m race: 

-"For Japanese collegiate 800-m athletes, VO2 remained elevated throughout the latter half of 800-m running, implying that the decline in running speed towards the end of the event could not be attributed to a fall in VO2. The ability to prevent a profound decrease of pH until 400-m may be the key to maintaining faster running speed near the end of the race." (VO2 peaked at 425m into the race)

Running economy:

 -Pole vaulters exhibited better oxygen cost than XC runners.

Simple question...IF PV have better O2 cost than XC runners…do you really think PV are more efficient or do you think the measurement sucks? 

-Stiff Achilles beneficial because of increase stiffness of tendon.

Pool Plyos:

-In one study they looked at doing sprint drills and plyos on the land versus in the water and looked at the change in sprint speed over 40-100m.  These weren't crazy fast people (mid 13s for 100), but the pool group improved speed to the same degree.

I love this study because it supports something I happened upon way back in HS, doing pool plyos.  Yes, you lose some of the stretch reflex and increase Ground contact time when you do it, but doing pool plyos and more importantly pool power work is a GREAT tool for distance runners who generally suck at it and are prone to injuries from that kind of stuff.  I love explosive pool work in particular, but this study shows that it at least works.

Individualization of Immune response:

-"The immune response reflected a change in the number of blood cells of the athletes after performing exhausting physical activity, these cells acquire their normal levels after a week recovery period. It is important to emphasize that in

an individual way each athlete showed a different response to training. The results presented in this study were an average, in some cases the athletes showed higher or lower values concluding that integral physical personalized training is strictly necessary for triathlon as a sport and also to avoid over training."

 I LOVE this study.  Why?  Because it shows the individual immune system response to exercise.  This has profound impact on recovery for athletes and is just another example of why individualization matters.  I'll have a blog on this soon.

Sleep:

-"One night of sleep disruption lowers the heart rate response and amplifies the mobilisation of NK-cells in response to acute exercise. These data indicate that altered sleep patterns could interfere with the trafficking of cytotoxic lymphocytes in response to acute exercise and might play a role in athlete infection susceptibility.

Self selecting intensity increases positive affective response:

 -"These results suggest that perceived autonomy is related to affective responses to exercise"
This was a cool little study that showed that when people were assigned an intensity that had higher negative affect and when they had a self chosen intensity for exercise they felt more positive affect.  What this means, is don't be anal about assigning exact paces for everything.  Save that for when you need it. 

 Toe exercises:

-"The towel gathering and the great toe flexor exercise significantly decreased MLA (arch length). In regard to the great toe flexor exercise, the tendency was stronger. On the other hand, the exercises of 2nd-to-5th toe flexors and 3rd-to-5th toe flexors increased MLA.

Training Volume of Olympic rower:

-"In the observed period, 5827km (127km/week) were covered by the W1x, including 4202km on water, 910km on ergometer, and 715km in running and cycling. When divided by intensity zones, 75.2% of the distance was distributed in zone 1. The percentage of zone 2 and zone 3 was 22.4% and 2.4%, respectively. After dividing the training year into preparatory period (October to middle of March) and competition period (middle of March to OG), it was found that the training at or around lactate threshold (zone 2) decreased significantly from 34.4% in the preparatory period to 8.7% in the competition period, which was sacrificed by increasing the training volumein zone 1 and 3 from 63.5% to 88.6%, and from 2.1% to 2.7%, respectively.

Very cool to look at the training volume and intensity and compare it to runners.

Supplements:

-Bakers yeast B glucon- Decrease cold symptoms post marathon and improves mucosal immunity post hard workout and decreases IL.

-Betaine increases GH and IGF-1 and decreases cortisol