Research Review is my monthly round up of the very latest sport and exercise science research. The premise is a simple one – I scour the journals for new manuscripts, pick the most eminent and then summarise them in plain English. On the 7th of each month subscribers get the latest issue sent direct to their inboxes with summaries of 8-10 new manuscripts and one classic – ‘From The Archives’ – study.
Not sure if Research Review is your thing? Or maybe you just want a sneaky little preview? If so, here’s just a taster of the kind of content you’ve been missing out on so far…
From Issue 1 – 7th June
The role of the calf muscles in landing
The majority of ACL injuries are non-contact in nature and occur during landing or cutting movements. During landing, anterior translation of the tibia in the sagittal plane is restrained by the ACL; forces acting anterior of the tibia therefore place greater stress on the ACL. Whilst the role of the hamstring muscles in counteracting anterior force is fairly well established, the role of the musculature on the other side of the knee joint is less clear.
Eight healthy male participants performed single-leg landings from heights of 30 and 60 cm. Kinematic data was sampled using Vicon motion analysis software and muscle activity of the hamstrings (HAM), gastrocnemius (GAS) and soleus (SOL) were monitored using EMG.
SOL exerted a posterior force on the tibia equivalent to 28–32% of HAM posterior force for both landing heights. HAM tended to be activated near the start of the landing cycle while peak SOL forces occurred toward the end of the cycle, perhaps an expected consequence of their differing fibre composition. Small GAS forces were present during the early landing stage, suggesting an initial role in stabilising the ankle.
- Outcome: The soleus, despite not crossing the knee joint, plays an important role in minimising ACL loading during landing.
Mokhtarzadeh H, Yeow CH, Goh JCH, et al. Contributions of the Soleus and Gastrocnemius muscles to the anterior cruciate ligament loading during single-leg landing. Journal of Biomechanics. 3rd June 2013 [epub ahead of print]. [doi:10.1016/j.jbiomech.2013.04.010].
From Issue 2 – 7th July
Foam rolling as a recovery tool
Despite the ever increasing popularity of foam rolling (FR), literature evaluating its effectiveness and modes of action is somewhat sparse. Graham MacDonald and his colleagues are a research group that are doing their best to try and shed some light on the whole FR situation.
Twenty strength trained males (3+ years experience; mean squat of 152 ± 25% bodyweight) performed an exercise session consisting of 10 sets of 10 back squats. Repetitions were completed at 60% of a predetermined 1RM and with 2 minutes inter-set recovery. Measurements including soreness, vertical jump and various direct muscle properties were taken immediately after the exercise session and then after 24 (24HR), 48 (48HR) and 72 (72HR) hours of recovery. Subjects completed either a FR or control (i.e. nothing) recovery intervention immediately after the exercise session and repeated this after each set of testing (i.e. every 24 hours). The foam rolling group performed 5 FR exercises; these targeted the anterior, lateral, posterior and medial aspects of the thigh in addition to the glutes. Subjects performed each of these 5 exercises for 2, 60 second bouts on each leg (a total of 20 minutes).
Results demonstrated that FR reduced perceived muscle soreness at 24HR (effect size (ES): 0.66), 48HR (ES: 1.03) and 72HR (ES: 1.02). FR appeared to attenuate decreases in vertical jump height at 24HR (ES: 0.49) and 48HR (ES: 0.81), however, there were substantial differences (~10%) in jumping ability between the two groups. The impact of this discrepancy on recovery capabilities should not be discounted. Given that losses in max isometric force were not reduced by FR, and that FR actually had a negative impact on several intramuscular measures, the authors suggest that any benefits of FR are primarily accrued through neural responses and connective tissue.
- Outcome: Prolonged, post-exercise foam rolling appears to be an effective tool for attenuating exercise-induced muscle soreness and impairments in jump height.
MacDonald GZ, Button DC, Drinkwater EJ, et al. Foam rolling as a recovery tool following an intense bout of physical activity. Medicine & Science in Sports & Exercise. 21st June 2013 [epub ahead of print]. [doi:10.1249/MSS.0b013e3182a123db].
From Issue 3 – 7th August
HMB may attenuate damage responses
ß-hydroxy-ß-methylbutyrate (HMB) is a metabolite of the amino acid leucine and becoming an increasingly popular supplement given its purported anti-catabolic effects. It has previously been demonstrated calcium salt forms of HMB (HMB-Ca) may reduce indices of muscle damage although new research now suggests that a free acid form of HMB (HMB-FA) may have a greater bioavailability than traditional HMB-Ca (HMB-FA achieving peak plasma concentration at 36 minutes versus 131 minutes in HMB-Ca). HMB-FA may also be better utilised by the tissues. Townsend et al looked to investigate the effect of HMB-FA on muscle damage markers following resistance exercise and also to examine whether cold water immersion (CWI) carried any additive benefit.
Forty resistance trained men (>1 years training experience) were randomised into four groups; a) placebo ingestion (PL), b) HMB-FA ingestion (HMB), c) placebo ingestion with CWI (PL-CWI) and d) HMB-FA ingestion with CWI (HMB-CWI). HMB-FA was taken in gel form, a 1 gram serving consumed 30 minutes prior to training and then subsequently at 2 and 6 hours following training. CWI consisted of immersion to the belly button in a 10-12oC ice bath for a period of 10 minutes. Subjects performed an initial resistance training session consisting of 4 sets of up to 10 repetitions of the squat (@80% 1RM), deadlift (@70% 1RM) and split squat (@70% 1RM), all with 90 seconds inter-set recovery. Subjects then performed a further 4 sets of up to 10 repetitions of the squat alone at 24 and 48 hours following the initial session. Blood samples were taken prior to training (PRE), immediately post (IP), 30 minutes post (30P), 24 hours post (24P), and 48 hours post (48P) training. Samples were analysed for circulating levels of TNF-α (a marker of the inflammatory response to muscle damage) and its associated receptor cell TNFR1.
The exercise protocol significantly elevated TNF-α in PL (p = 0.006) and CWI (p = 0.045) at IP but not in either HMB group. Mean percent changes show TNF-α significantly increased from PRE to IP for only PL and CWI groups (p < 0.05) while the percent change of TNF-α for HMB-FA and HMB-FA-CWI was not significant. TNFR1 receptor expression was elevated in PL (p = 0.023) and CWI (p = 0.02) at 30P compared to PRE while both HMB-FA treated groups did not increase significantly. There was no additive benefit of HMB and CWI. The authors intend to report additional creatine kinase (another marker of damage) as part of a separate publication.
- Outcome: Acutely, HMB-FA supplementation at the prescribed dosage may attenuate the initial immune response to a single session of intense resistance exercise.
Townsend JR, Fragala MS, Jajtner AR, et al. ß-hydroxy-ß-methylbutyrate (HMB)-free acid attenuates circulating TNF-α and TNFR1 receptor expression post-resistance exercise. Journal of Applied Physiology. 1st August 2013 [epub ahead of print]. [doi:10.1152/japplphysiol.00738.2013].
Like what you see? All the info regarding signing up can be found here and I’ve also written a blog post outlining everything you need to know about Research Review here. I hope to welcome you aboard soon!