Research Galore!- Summary of 2013 ACSM research



Each year for the biggest sports science conferences, I try and go through all of the abstracts being presented.  It’s the second best option, since attending isn’t an option due to my schedule.  Besides seeing the new research that is out there, you get to notice trends.   It gives you a good idea on where the field is headed as a whole.  As readers of my blog, you get to benefit from me combing through about 600 pages of abstracts, and get to see the studies that caught my attention.

In the running world, studying barefoot and minimalism seemed to be the biggest trend, which shouldn’t be surprising!

What I will do, to keep things simple is cite the study, so that you can look it up if you want.  To download all of the abstracts go to acsm.org.

I’ve separated them out into categories, and may include some notes if I think it’s interesting:


Barefoot/Minimalism:
-Plantar Aponeurosis plays major role in energy return from arch. (Quantification of the Returned Force in the Arch During Barefoot Running. Emily L. Martin)

-In trained mid-forefoot runners, no difference in efficiency between shoes and barefoot (No Difference in Metabolic Efficiency in Barefoot and Shod Conditions in Experienced Mid-Forefoot Runners)

-Muscle activity of the Peroneus Longus was reduced running barefoot versus shod, as well as a tendency for soleus activation to be lower barefoot  (The Effect of Shod Versus Barefoot Running on Lower Limb Muscle Activation)

-No difference between injuries based on foot strike pattern. Self reported injuries and footstrike. (No Differences in Self-reported Injuries or Performance Between Characterized Foot-strike Patterns Amongst US Army Soldiers)

-Increasing stride rate by 8% reduced braking impulse. (Reduced Ground Reaction Forces during Running Remain after Training at Increased Step Rate)

-Study found that impact force varied between an obvious heel strike and a subtle heel strike.  Seems important that we just can’t classify stuff into heel versus forefoot (
Influence of Different Rear Foot Strike Strategies on Impact Force During Running)

-24% of rear-foot strikers immediately changed to mid or forefoot strike when changed to minimalist shoes (The Effect of Footwear on Foot Strike Pattern in Running)

-Barefoot training program causes lighter, quicker strides and longer activation of the gastrocnemius, but not an increase in the intensity of contraction.  (Effects of a Barefoot Training Program on Muscle Activation and Foot Contact Time)

-Instructed barefoot running causes reduction in ground reactions forces ( Reduction in Ground Reaction Forces with Instructed Barefoot Running)
-Differences between rearfoot and forefoot strike:
The results suggest natural RF and FF runners may run with different muscle mechanics despite similar ATMA lengths. More economical natural FF runners may run with decreased plantar flexor force required to produce a given joint moment whereas more economical natural RF runners may run with increased plantar flexor force but optimal muscle shortening velocities. Therefore, muscle forcemrather than muscle work may dictate running economy in natural FF runners. A smaller correlation between ATMA and VO2 with FF running compared to RF running may be a result of greater plantar flexor force required with the FF pattern.” (The Relationship Between Achilles Tendon Moment Arm and Running Economy in Rearfoot and Forefoot Runners)


Genetics:
-Blood lactate rates for same exercise varies based on if you different polymorphisms (SLC 16A1 Gen Polymorphism in Relation to Blood Lactate Concentration in Endurance Athletes M Soria1)

-Aerobic exercise causes DNA methylation (think Epigenetic changes) (Alterations in DNA Methylation Associated with Aerobic Exercise Training)

-Fish oil supplementing alters DNA methylation of inflammatory related genes (Pilot Study : DNA Methylation Of Selected Genes Following n-3 Dietary Supplementation)

-Difference in DNA Methylation between females and males.(The DNA Methylome of Human Skeletal Muscle

          
Nutrition
Exercising in fasted state activates autophagy in mice. (Autophagy In Muscle Of Mice During Exercise In A Fasted Or In A Fed State)

-          Dietary Protein Intake Modulates Satellite Cell Myostatin Expression Following A Bout Of Resistance Exercise

-Leucine intake decreases muscle damage and delayed onset muscle soreness (Effect of Leucine-enriched Essential Amino Acids Mixture on Recovery from Muscle Damage and DOMS Following)

-Beta Alanine improves cycling performance (Effect Of β-alanine And Sodium Bicarbonate On Muscle Buffering Capacity And High-intensity Cycling Capacity)


RPE/Perception:
-Having someone on your run, tends to make you run slower but enjoy it more versus doing it alone. (The Effect Of Peer Influence On Exercise Intensity And Enjoyment During Outdoor Running In Collegiate Distance Runners)

-There is a strong relationships between RPE and blood lactate levels in D3 CC runners. Possible that lactate serves a mediator for perception of exertion. (Relationship between Rate of Perceived Exertion and Blood Lactate Concentration in Female Cross Country Runners)

-Nocebo, and placebo affected peak power. Placebo improved performance, while Nocebo showed an increase in RPE. ( The Placebo and Nocebo Effects on Peak Minute Power during Incremental Arm Crank Ergometry)
            -NOTES: Love this study.  Shows the impact of perception on performance!


Ice Baths/Icing:
-Ice baths didn’t might help for recovery between two different 1600m time trials. (The Effect of Cold Water Immersion on Repetitive 1600m Run Performances in College Aged Distance Runners

-(Recovery Using Different Water Immersion Temperatures Accelerates Post-exercise Cardiac Parasympathetic Reactivation

-Cold water immersion didn’t have an effect on any markers of recovery except for a small effect on DOMS. (Effects of Seated and Standing Cold Water Immersion on Recovery from Simulated Intermittent Sprint Sport

- Taking an ice bath did not improve performance on a 2nd 5km run. (Cold Water Immersion as a Recovery Technique Between Two 5 km Time Trials)


Respiratory system:
-          Mechanical ventilator constraints limit performance.(Effects Of Heliox On Respiratory Mechanics And Cycling Performance In Endurance-trained Men And Women
-           

Efficiency/Economy:
-Gross efficiency decreases during cycling time trials from  500m to 40,000m, with biggest reduction during shorter time trials.  Changes in muscle fiber recruitment didn’t explain the change. (Changes in Gross Efficiency in Relation to Time Trial Length)
NOTE:  This study is one of those “duh” stories, but one that needed to be done.  We get less efficient as we fatigue.  Research/training should go into how to minimize this decrease in efficiency from start to finish. Perhaps this is where strength training or strength endurance work can help.  But it’s also important because in certain areas of research, efficiency is calculated as being steady…

-Plyos improve running performance without a change in Running Economy/Oxygen Consumption.  Study suggested that Titin in Vastus Laterulus didn’t act as spring-like source of free energy(The Effect of Plyometric Training on Running Economy and Titin)

-Gender differences in running economy may be from differences in vertical acceleration.  Women accelerate less in certical axis than men. (Vertical Accelerations are Associated with Gender Differences in Running Economy Among Intercollegiate Runners)

Recovery:
-Stress causes changes in perception of  how we perceive pain, RPE, muscular pain, and other factors when lifting (Affective Responses To Strenuous Resistance Exercise Vary By The Perception Of Chronic Psychological Stress

-          Sleep quality is more important than sleep quantity in cross country runners when trying to protect against stress and improve immune system (Sleep, Stress, And Sickness In Collegiate Cross Country Runners While In Season)
-Massage- To simulate massage, cyclic compressive loading was given to a bunch of Rats.  This compression stuff, increased pp70s6k, which is a marker for protein synthesis.  Authors suspect that massage may upregulate mTOR pathway which helps increase muscle hypertrophy.   (Mechanical Modulation Of The Mtor Pathway Is Dependent Upon The Magnitude Of Cyclic Compressive Load)

-Massage- Similar study looked at massage simulator in rats.  Found that gene expression was increased with massage. (Immunomodulatory Genes in Skeletal Muscle are Responsive to Mechanical Loading Following Massage Mimetic).

Tapering:
-Tapering in endurance athletes causes a growth in FT muscle fibers (5% a week for 3weeks).  Study found during taper, molecular pathways for suchc changes are activated (Molecular Insight into Fast-Twitch Muscle Fiber Remodeling with Taper)
            -NOTE:  This is a little known phenomenon that has generally been regulated to sprint/power athletes.  You see a rebound effect in sprinters where it’s thought that a big taper allows recovery and a rebound so that Fast Twitch fiber percentage/efficiency/size all improves.  In distance runners, with big tapers you see the same effect, as demonstrated by this study.  This is important!!! It’s one of the reasons why mid-distance/FT orientated athletes might do really well with a big taper, while a ST athlete might feel horrible after a big taper.

Stretching:
-Yoga twice a week did not improve muscle tightness or flexibility, and there was a trend toward worse mile times (Effect of Yoga on Mile Time Performance in Male High School Runners

-Dynamic stretching does NOT increase hamstring flexibility, or improve running economy, BUT it does improve performance (Dynamic Stretching On 5-km Performance And Running Economy In Collegiate Cross-country Runners)

Elites:
-Compared 13 elite (3:41avg 1500m time) and 15 subelite portugese runners on VO2max and 600m supramaximal test.  ELITES had lower maximum accumulated oxygen debt.  VO2max did not differ.  During 600m supramaximal test, aerobic contribution was 73% for elites, but only 65% for sub elites. (Maximal Oxygen Deficit And Race Performance In Portuguese Elite Middle Distance Runners)
            -Note: Interesting study, and findings.  Would like to see full data, but interesting that during 600m supramaximal test, elites were more aerobic.

-Compared elite European vs. Elite Kenyans.  VO2max was similar. Kenyan long distance runners had better Running Economy than Kenyan middle distance runners. Kenyans had better running economy than Europeans ( Maximal Aerobic Exercise Capacity And Running Economy Of Elite Kenyan Middle- And Long-distance Runners Compared With European Runners)

-Junior athletes in track tend to peak much earlier, running their best times (age 21) than track athletes who end up Olympic finalist (25.6yrs). Only 23.6% of JR medalist won medals as Senriors, and only 29.9% of seniors won junior medals. (Career Performance Progressions of Junior and Senior Elite Track and Field Athletes)

Physiology:
-Study found different trends in muscle fiber recruitment. It’s interesting because not many studies or thought is given to different fiber recruitment patterns.  The study concludes “individuals possessing a larger proportion of hybrid myofibers appear to largely rely on slow myofibers. Furthermore, individuals with a lower prevalence of hybrid myofibers likely have a more uniform activation pattern across fiber type, which may potentially reduce the overall load on a given fiber type.” (Myofiber Composition and Fiber Type-Specific Expression of Oxidative Capacity-Related Genes Following Acute Aerobic Exercise)

-Recovering in hypoxia post workout blunted oxidative stress. (Effect of Hypoxic Recovery Post-Exercise on Blood Oxidative Stress Markers)
            NOTE: I really like this study, because it looks at how the recovery after a workout can potentially impact training adaptations.  By changing the environment that you are in, or the things you do during recovery, it could alter training adaptations.  This is the first step in studies, but some very interesting possibilities are there. Another study, below, found that really high altitude changed adaptations.

- Following up the above study, this one looked at recovery at 5,000m simulated altitude after a 90min cycling session.  They found that spending the next 6hrs at really high altitude inhibited gene expression associated with mitochondrial development, but did not effect glycogen resynthesis. (Mitochondrial Related Gene Expression is Suppressed After Simulated High Altitude Exposure)

-Changing muscle fiber types is difficult.  They’ve found that transitioning fibers a lot of damage is needed in animal models.  To find out why, this study blocked stretch activated ion channels, and found that it resulted in a 100% fast twitch transition following eccentric exercise. (Stretch-Activated Ion Channels Are Essential for Fiber Type Transition in Eccentric Exercised Muscle)

Drugs:
-Vaccinations- performing exercise immediately after, in mice, affects the effectiveness of Flu vaccine (Vaccination And Exercise: How Varying Durations Of Exercise Immediately Post Vaccination Affect Influenza Vaccine Response)

-Interesting study gave 19 Caucasian runners and 20 Kenyan runners and gave them EPO for 4 weeks.  In Caucasians, Hematocrit went from 41.9 to 49.2 with EPO, performance improved from 11:08 to 10:30.  Then performance was still at 10:46 after being off the drug for 4 weeks.  In Kenyans, Hematocrit went from 46.0 to 49.9, while performance went from  9:20 to 8:55, and was still at 9:02 after 4 weeks off drug. ( Blood Parameters and Running Performance of Kenyan and Caucasian Endurance Trained Males After rHuEpo Administration)

-Thyroid- Kind of pertinent.  A study looked at giving T4 to normal thyroid people. It found that T4 reduced individual maximal fat oxidation rates. (Effect of Short-term Thyroxine Supplementation on Substrate Utilization during Exercise)


Biomechanics/Injury:
-Functional movement screens are poor predictors of injury. (Functional Movement Screen is a Poor Predictor of Injury in Division I Athletes)

-Trained runners have different gait patterns than untrained.  The three big differences were max hip angle, hip angle at foot strike, hip angle at midstance, footstrike difference from center of mass. Those factors explained 48.% of variance.  Angle angle at foot strike, knee angle at foot strike, and center of mass drop explained 24.7% of variance, while Center of mass rise included 15.3%.(Trained Collegiate Runners Exhibit Different Principal Components of Running Biomechanics Than Untrained Individuals)

4 comments:

  1. Thanks a lot for posting this stuff Steve. There is a ton of info to digest here.

    ReplyDelete
  2. Anonymous4:12 PM

    A lot of great information. Now I need to let it settle in and see where I can make some adjustments in my coaching. Thank you so much for posting all of this!

    ReplyDelete
  3. Awesome summary and this is really good because I find most of this as jargon. Somehow, I managed to understand the concept and scientific explanations of the studies above.

    ReplyDelete
  4. kanny1:29 PM

    Another thanks for this summary. I really can't wait to get my hands on some of these studies to analyze their data, especially the fiber type/ion channels and the fasted state results in autophagy ones.

    ReplyDelete

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