Yael Milgrom

Achilles Tendons Hypertrophy in Response to High Loading Training

Background: Whether the human Achilles tendon undergoes hypertrophic changes as measured by an increase in cross-sectional area, in response to endurance training exercise remains in question. We investigated the hypothesis that transition from civilian life through 6 months of elite infantry training would induce adaptive Achilles tendon hypertrophy. Methods: Seventy-two new elite infantry recruits had the cross-sectional area of their Achilles tendons measured at a point 2.5 cm proximal to the Achilles insertion by ultrasound before beginning elite infantry training. Measurements were repeated by the same ultrasonographer for those recruits who were still in the training program at 6 months. Prior to beginning the study the intraobserver reliability of the ultrasonographer’s Achilles tendon measurements was calculated (intraclass correlation coefficient = .96). Fifty-five recruits completed 6 months of training. Results: The mean cross-sectional area of their right Achilles tendon increased from 47.0 ± 11.2 to 50.2 ± 9.6 mm2 (P = .037) and the left Achilles tendon from 47.2 ± 8.9 to 51.1 ± 8.3 mm2 (P = .013). The change in cross-sectional area did not correlate with subject height, weight, prior sport history, or jumping and running abilities. Conclusions: An abrupt stimulus of 6 months of elite infantry training was adequate to induce hypertrophic changes in the Achilles tendon. This is the first human prospective study showing an increase in the Achilles tendon cross-sectional area in response to rigorous endurance type training. The finding supports the hypothesis that the Achilles tendon in response to sufficiently high and sustained loading can remodel its morphological properties and thereby strengthen itself. Level of Evidence: Level II, etiology study.

The effect of high versus low loading on bone strength in middle life.

While bone mass and geometry are largely genetically determined, mechanical loading is considered to be an important additional determinant. This study investigates to what extent very high mechanical loading begun at a young age and sustained afterward can affect tibia bone mass and geometry in middle age. Cohorts from a common ethnic background, with a history of very high and very low tibia bone loading based on an assessment of their activities according their strain levels were compared. The study hypothesis was that the tibia bone density and geometric strength parameters would be greater in the high bone loading cohort. Subjects from a group of elite infantry recruits who sustained a 31% incidence of stress fractures during their basic training in 1983, were reviewed 25 years later. The tibia bone strength of 25 of these soldiers, 11 of whom had sustained stress fractures, was compared to a group of 20 subjects who received exemption from military service in 1982-5 because they were religious scholars and who continued these studies afterwards. Anthropometric measurements were made. The bone density and geometric strength of the tibia was assessed by quantitative computerized tomography (QCT). The average daily dietary intake and metabolic expenditure of subjects were assessed by questionnaires. At the 25 year follow-up soldiers were on an average 3 cm taller than the religious scholars (p=0.02) and had lower abdominal girths (p=0.03). There was no difference in the tibia cortical density between cohorts in spite of the fact that the religious scholars had lower daily calcium intakes (p=0.02). Soldiers had stronger tibias based on geometric engineering criteria. The mean area moments of inertia (p=0.02, p=0.04) and polar moments of inertia (p=0.02) were 16% larger in the soldier cohort. By multivariate regression analysis greater height, weight and daily energy expenditure were related to larger bone geometric strength parameters. According to semipartial eta-square analysis, between 39% to 45% of the variance in the area moments of inertia between the cohorts was attributable to these three parameters. The religious scholars burned less calories daily, principally because they did no sport activity (p=0.001). There was no difference in tibia bone strength parameters between soldiers who did and did not sustain stress fractures in their 1983 basic training. In conclusion, in a middle age population with a common ethnic origin, the high bone loading cohort had stronger tibias than the low bone loading cohort based on larger geometric strength properties and not because of higher cortical density. In spite of being at the extremes of the bone loading spectra, the tibia area moment of inertia of the two cohorts in this study differed by only 16%, with part of this difference attributable to factors other than bone loading. We do not know for sure if the difference in the geometric properties is related to high bone loading or whether people with stronger bones are more likely to engage in high bone loading. Healthy male subjects who sustained stress fractures at a young age do not have weaker tibias at middle age according to QCT measurements.

The Effect of Very High versus Very Low Sustained Loading on the Lower Back and Knees in Middle Life

To evaluate the effect of the extremes of long term high and low physical activities on musculoskeletal heath in middle age, a historical cohort study was performed. The MRI knee and back findings of 25 randomly selected subjects who were inducted into the armed forces in 1983 and served at least 3 years as elite infantry soldiers were compared 25 years later, with 20 randomly selected subjects who were deferred from army service for full time religious studies at the same time. Both cohorts were from the same common genome. The two primary outcome measures were degenerative lumbar disc disease evaluated by the Pfirrmann score and degenerative knee changes evaluated by the WORMS score. At the 25-year follow up, the mean Pfirrmann score (8.6) for the L1 to S1 level of the elite infantry group was significantly higher than that of the sedentary group (6.7), (P = 0.003). There was no statistically significant difference between the WORMS knee scores between the two cohorts (P = 0.7). In spite of the much greater musculoskeletal loading history of the elite infantry cohort, only their lumbar spines but not their knees showed increased degenerative changes at middle age by MRI criteria.

Pregnancy-Onset Inflammatory Bowel Disease: A Subtle Diagnosis

Background Inflammatory bowel diseases (IBDs) are commonly diagnosed during the reproductive years. IBD first manifested during pregnancy (pregnancy-onset IBD [POIBD]) is still an undescribed entity. The aim of the study was to evaluate the characteristics and maternal and neonatal outcomes of patients with POIBD. Methods Data of all pregnant women with IBD within a single multidisciplinary referral clinic, IBD-MOM, between 2011-2016, were analyzed. Maternal and neonatal characteristics and outcomes were compared between the POIBD group and those diagnosed before pregnancy (non-POIBD). Results We identified 237 women, 31 (15%) from the POIBD group and 206 (85%) from the non-POIBD group. Eight (3.5%) patients experienced early spontaneous pregnancy loss, all in the non-POIBD group. The POIBD diagnosis occurred in 16 (52%) patients during the first trimester, 10 (32%) in second trimester, and 5 (16%) during third trimester. Diagnosis of ulcerative colitis (UC) was significantly more common in the POIBD group compared with the non-POIBD group (22/31, 71% vs 50/206, 24%, respectively, P < 0.001). More UC than Crohns disease patients had active disease during pregnancy (69% vs 50%, P = 0.03, respectively). POIBD patients experienced vaginal delivery in 100% of births, compared with 164 (79.6%) in the non-POIBD group (P = 0.017). The mean gestational age at birth and the neonatal weight were similar among the study groups; 38.6 weeks and 3040 g for POIBD patients, compared with 38.7 weeks and 3055 g in the non-POIBD group. Conclusions POIBD is a unique clinical entity, and the diagnosis is mostly UC. However, the maternal and neonatal outcomes are similar.

Cardiovascular and bone health of former elite infantry soldiers at middle life

BackgroundThe long term implications of elite infantry service on cardiovascular health and cortical bone width at middle age has not been studied. The purpose of this study was to compare the cardiovascular health and cortical bone thickness of former elite infantry soldiers at middle life with a sedentary population of religious scholars using seven factors associated with cardiovascular risk and QCT tibial cross sections 8 cm above the ankle joint.ResultsTorah scholars had a higher 5 year risk for a fatal or non fatal cardiovascular event (p = 0.008) than former elite infantry soldiers. The former elite infantry soldiers had wider tibia cortices than Torah scholar (p = 0.003).ConclusionsThis study shows that former elite infantry soldiers who performed strenuous physical activity during their military service and continued physical activity in their subsequent life, had stronger tibias based on increased cortical width and a modest decrease in cardiovascular risk at middle life compared to sedentary Torah scholars.

The effect of orthotics on in vivo axial tibial and second metatarsal strains

Background: In a previous military study a custom-made tri-layer polyurethane shoe orthotic was shown to be effective in lowering the incidence of stress fractures in infantry recruits. Stress fractures are caused by repetitive high strains. Objective: To compare the effect of tri-layer polyurethane orthotics with other types of orthotics on in vivo strains at sites where stress fractures are common. Design: Subjects underwent surgical implantation of strain gauged staples to the dorsal surface of the midshaft 2nd metatarsal and to the medial surface of the midshaft tibia. Setting: University Hospital. Patients: Two male members of the research staff aged 40 and 54. Measurements: In vivo simultaneous peak-to-peak axial compression-tension strains during treadmill walking at 5 km/h while wearing standard army boots and Nike Air Max running shoes with and without either a non custom pre-fabricated orthotic with a three-quarter length thermocork module, a semirigid custom-made orthotic, with a three-quarter length polypropylene module made from nonweightbearing neutral subtalar position casts, a soft full length custom-made orthotic fabricated from 60 durometer plastazote, and a soft full length custom-made orthotic with a neutral heel post molded from three layers of polyurethane of different density (grade 80 upper layer, grade 60 middle layer and grade 80 lower layer). Results: Only the custom polyurethane composite orthotic was affective in lowering both peak-to-peak compression-tension 2nd metatarsal and tibia strains for both subjects when worn with army boots. When worn with Nike Air Max shoes the polyurethane composite orthotic lowered the peak-to-peak compression-tension 2nd metatarsal but not tibia strains. Limitations: Small subject number, each with a different foot type. Conclusions: The lower peak-to-peak compression-tension tibial and 2nd metatarsal strains while wearing army boots with custom polyurethane composite orthotics can explain the observed lower incidence of stress fractures among military recruits who used these orthotics.