Measurements of thermal properties of icy Mars regolith analogs

In a series of laboratory experiments, we measure thermal diffusivity, thermal conductivity, and heat capacity of icy regolith created by vapor deposition of water below its triple point and in a low pressure atmosphere. We find that an ice-regolith mixture prepared in this manner, which may be common on Mars, and potentially also present on the Moon, Mercury, comets and other bodies, has a thermal conductivity that increases approximately linearly with ice content. This trend differs substantially from thermal property models based of preferential formation of ice at grain contacts previously applied to both terrestrial and non-terrestrial subsurface ice. We describe the observed microphysical structure of ice responsible for these thermal properties, which displaces interstitial gases, traps bubbles, exhibits anisotropic growth, and bridges non-neighboring grains. We also consider the applicability of these measurements to subsurface ice on Mars and other solar system bodies

Hamstring Injury Prevention in Soccer:Before or After Training?

We examined the effects of a 12-week program of Nordic hamstring exercises (NHE), administered before or after football training, upon eccentric hamstring strength, muscle activity, and architectural adaptations. Amateur soccer players were randomized into three groups. The control group (CON; n=11) undertook core stability exercises, whereas a periodized NHE program was delivered either before (NHEBEF; n=10) or after (NHEAFT; n=14) biweekly training sessions. Outcome measures included peak torque and concomitant normalized peak surface electromyography signals (sEMG) of the biceps femoris (BF) and medial hamstring (MH) muscles during knee flexor maximal eccentric contractions, performed at 30°.s-1. Ultrasonography was used to determine BF muscle thickness, muscle fiber pennation angle, and fascicle length. Performing the NHE derived likely moderate peak torque increases in both NHEBEF (+11.9%; 90% confidence interval: 3.6%-20.9%) and NHEAFT (+11.6%; 2.6%-21.5%) vs CON. Maximum sEMG increases were moderately greater in the BF of both NHE training groups vs CON. There were likely moderate increases in BF muscle thickness (+0.17 cm; 0.05-0.29 cm) and likely small pennation angle increases (+1.03°; -0.08° to 2.14°) in NHEAFT vs CON and NHEBEF. BF fascicle length increases were likely greater in NHEBEF (+1.58 cm; 0.48-2.68 cm; small effect) vs CON and NHEAFT. A 12-week eccentric hamstring strengthening program increased strength and sEMG to a similar magnitude irrespective of its scheduling relative to the football training session. However, architectural adaptations to support the strength gains differed according to the timing of the injury prevention program

Scheduling of eccentric lower limb injury prevention exercises during the soccer micro-cycle: Which day of the week?

Scheduling eccentric-based injury prevention programs (IPP) during the common 6-day micro-cycle in soccer is challenged by recovery and tapering phases. This study profiled muscle damage, neuromuscular performance, and perceptual responses to a lower limb eccentric-based IPP administered 1 (MD+1) vs 3 days (MD+3) postmatch. A total of 18 semi-professional players were monitored daily during 3 in-season 6-day micro-cycles, including weekly competitive fixtures. Capillary creatine kinase concentration (CK), posterior lower limb isometric peak force (PF), counter-movement jump (CMJ) performance, and muscle soreness were assessed 24 hours prior to match-day (baseline), and every 24 hours up to 120 hours postmatch. The IPP consisted of lunges, single stiff leg dead-lifts, single leg-squats, and Nordic hamstring exercises. Performing the IPP on MD+1 attenuated the decline in CK normally observed following match play (CON: 142%; MD+3: 166%; small differences). When IPP was delivered on MD+3, CK was higher vs CON and MD+1 trials on both MD+4 (MD+3: 260%; CON: 146%; MD+1: 151%; moderate differences) and MD+5 (MD+3: 209%; CON: 125%; MD+1: 127%; small differences). Soreness ratings were not exacerbated when the IPP was delivered on MD+1, but when prescribed on MD+3, hamstring soreness ratings remained higher on MD+4 and MD+5 (small differences). No between-trial differences were observed for PF and CMJ. Administering the IPP in the middle of the micro-cycle (MD+3) increased measures of muscle damage and soreness, which remained elevated on the day prior to the next match (MD+5). Accordingly, IPP should be scheduled early in the micro-cycle, to avoid compromising preparation for the following match

Whole body cryotherapy and recovery from exercise induced muscle damage: A systematic review

Introduction Cold therapies are used regularly in medicine for their analgesic and anti-inflammatory effects. Whole-body cryotherapy (WBC) involves exposure to air maintained between -110 and -160oC, and is hypothesised to reduce pain, local and systemic inflammation. WBC has recently become popular in an exercise and sporting context as a recovery method after skeletal muscle damage, however, research examining the efficacy of WBC in an athletic context is minimal. This review seeks to summarise the evidence for the effects of WBC on exercise recovery measures. Methods Electronic database searches were conducted from March to April 2013. Six large online databases were used; MEDLINE, SPORTDiscus, Scopus, Web of Science, PubMed and AMED. The search targeted human studies with an exercise task, and WBC intervention. Results included randomised controlled trials (RCT’s), uncontrolled trials and crossover designs. Results A total of 8 studies were included in the review. Two RCT’s, four crossover trials and two uncontrolled trials were identified. Five studies showed WBC had no effect on markers of muscle damage or inflammation post exercise, while 3 studies show a positive effect. Three out of the eight studies measured maximal muscle force production and subjective pain levels following exercise and WBC, with two showing WBC had a positive effect on muscle force recovery and pain. A meta-analysis was not conducted due to the heterogeneity of the studies. Conclusion The current evidence for the efficacy of WBC on exercise recovery is unclear. Published studies report mixed findings, and the study designs make these results difficult to interpret. As WBC is proposed as an aid to recovery in an athletic population, repeated measures of performance, muscle force production and pain are of importance to the athlete, however, are minimally reported in the literature. Cold water immersion (CWI) is widely used in an athletic setting for recovery, and has much literature supporting its use for the reduction of pain post-exercise. Well-designed RCT’s with controlled exercise interventions targeting performance measures are needed, in particular comparison of WBC with CWI data is needed for evaluation

Effects of whole body cryotherapy and cold water immersion on immune and inflammatory markers following exercise induced muscle damage

Introduction: Cold therapies are used regularly in medicine for their analgesic and anti-inflammatory effects. Whole-body cryotherapy (WBC) involves exposure to air maintained between -110 and -160oC, and is hypothesised to reduce pain, local and systemic inflammation. WBC has recently become popular in an exercise and sporting context as a recovery method after skeletal muscle damage. However, research examining the efficacy of WBC in an athletic context is minimal, in particular, studies comparing WBC to currently accepted recovery methods are lacking. Cold water immersion (CWI) is a widely researched and applied method of skeletal muscle recovery in sport science. As yet, no study has compared the proposed new method of WBC and the currently practiced method of CWI. We have designed a randomised control trial to examine the efficacy of WBC, as compared with CWI on recovery from a bout of eccentric muscle damage. Methods: Sixty healthy male subjects will perform skeletal muscle function tests and an eccentric muscle damage protocol of their left quadriceps femoris, using an isokinetic dynamometer. They will then be randomly assigned to one of 3 groups, WBC, CWI or a passive recovery control (PAS). The WBC will expose subjects to -160°C for 3min, using cold air. The CWI condition involves whole body exposure for 3min, in water maintained at 12°C. The PAS will have subjects seated comfortably at room temperature following the exercise protocol. Blood samples, muscle functional measurements and pain reports will be taken before muscle damage, immediately following damage, prior to therapy administration and post therapy. Further follow up measures to be taken 6 h post, 24 h and 7 days post. Blood samples will be analysed for changes in interleukins 6, 8 and 10, creatine kinase and leukocyte population kinetics. Results: Testing is being conducted. Results to be presented at the international society of exercise immunology (ISEI) symposium in September 2013