Effects of Group Running on the Training Intensity Distribution of Collegiate Cross-Country Runners.

ABSTRACT: Farrell III, JW, Dunn, A, Cantrell, GS, Lantis, DJ, Larson, DJ, and Larson, RD. Effects of group running on the training intensity distribution of collegiate cross-country runners. J Strength Cond Res 35(10): 2862-2869, 2021-Collegiate cross-country training is often conducted and prescribed in a group setting. This may result in the application of an inappropriate training stimulus to athletes due to potentially different physiological responses to the same training prescription. The aim of this investigation was to quantify the training intensity distribution (TID) of a collegiate cross-country team and the associated physiological adaptions. Sixteen subjects, 8 male subjects and 8 female subjects, performed a graded exercise test before and after observational period to determine peak oxygen consumption (V̇o2peak), the speed (S@), heart rate (HR@), and oxygen consumption (V̇o2@) associated with 2 and 4 mmol·L-1 of blood lactate. Training intensity distribution was quantified by assessing time spent in 3 intensity zones calculated as zone 1 (low intensity, HR values HR@2 and HR@4). No statistical differences were observed between male subjects and female subjects for percent of training time spent in zones 1, 2, and 3. No significant interactions were observed between sex and time for performance variables. Male subjects and female subjects improved V̇o2peak, S@4, and V̇o2@4 with male subjects also increasing V̇o2@2. No significant differences were observed between male subjects and female subjects when comparing percent changes for variables. Examining individual data showed that 2 female subjects experienced performance decrements and trained proportionally more in zones 2 and 3 compared with the overall group. The TID and performance decrements of the 2 highlighted subjects suggest that conducting training in a group setting may potentially be detrimental for some collegiate runners.

Aerobic Exercise Supplemented With Muscular Endurance Training Improves Onset of Blood Lactate Accumulation.

Farrell III, JW, Lantis, DJ, Ade, CJ, Cantrell, GS, and Larson, RD. Aerobic exercise supplemented with muscular endurance training improves onset of blood lactate accumulation. J Strength Cond Res 32(5): 1376-1382, 2018-Studies have shown that when aerobic exercise is supplemented with muscular endurance training metabolic adaptions occur that result in the delay of the onset of blood lactate accumulation (OBLA). However, previous studies have not explored any submaximal cardiorespiratory adaptations that may result from this training protocol. The aim of the current investigation was to evaluate the effect of supplementing an aerobic exercise training program with a muscular endurance training program on various cardiorespiratory and metabolic measurements. Fourteen aerobically active men performed an incremental exercise test to determine the OBLA, gas exchange threshold (GET), and maximal oxygen uptake (V[Combining Dot Above]O2max). Maximal strength was measured using 1 repetition maximum (1RM) for leg press (LP), leg curl (LC), and leg extension (LE). Eight subjects supplemented their aerobic activity (experimental [EX] group) with 8 weeks of muscular endurance training, while 6 continued their regular aerobic activity (control [CON] group). No significant group differences were observed for all pretraining variables. After 8 weeks of training, no significant differences in body mass, GET, and V[Combining Dot Above]O2max were observed for either group. However, the EX group showed a significant improvement for both absolute and relative V[Combining Dot Above]O2 at OBLA compared with the CON group. Leg curl and LE 1RM assessments for the EX group showed a significant improvement compared with CON group. Muscular endurance training did not improve GET and V[Combining Dot Above]O2max, but significantly increased V[Combining Dot Above]O2 at OBLA, LP, and LC. These findings suggest that this training protocol maybe useful in the development of submaximal aerobic performance and leg strength for endurance athletes.

Eight Weeks of High-Volume Resistance Training Improves Onset of Blood Lactate in Trained Individuals.

Lantis, DJ, Farrell, JW, III, Cantrell, GS, and Larson, RD. Eight weeks of high volume resistance training improves onset of blood lactate in trained individuals. J Strength Cond Res 31(8): 2176-2182, 2017-The purpose of this study was to determine if onset of blood lactate (OBLA) using the fixed at 4 mmol·L method could be delayed by supplementing high-volume resistance training (HVRT) to existing endurance training programs. There were 20 male subjects who participated in the study; 11 experimental (EX) (22.8 ± 4.6 years) and 9 controls (CON) (23.2 ± 5.8 years). An incremental cycling test was performed to determine maximal oxygen uptake, OBLA, maximum power, and time to exhaustion. Additionally, strength of the leg press (LP), leg curl (LC), and leg extension (LE) was assessed in both groups. Participants continued their ongoing endurance training, whereas the EX group supplemented their training with HVRT twice weekly for 8 weeks, performing 4 sets of 15 repetitions of LP, LC, and LE. Change score (post-pre) analysis was measured, using t-tests to compare the differences between groups, to eliminate outside variables that may have affected testing performance. Significance was set at p ≤ 0.05. No significant group differences in baseline measures were observed. A significant difference was observed for OBLA at 4 mmol·L (EX: 18.17 ± 15.36 W and CON: -3.52 ± 20.13 W, p < 0.02). A significant difference was observed for LP (EX: 39.09 ± 25.87 kg and CON: 4.22 ± 34.65 kg, p < 0.02) and LC (EX: 22.84 ± 8.7 kg and CON: -1.47 ± 8.2 kg, p < 0.01). Supplementing HVRT in endurance-trained individuals delayed OBLA at 4 mmol·L and improved leg strength. The HVRT used in the current study may be a useful training style for endurance-trained individuals.

Ankle dorsiflexion asymmetry and the relationship with walking performance in people with multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a neurological disease characterized by demyelination disrupting the central nervous system. Persons with MS may exhibit symptomatic strength asymmetry (SA) that impacts motor gait and ankle mobility. The purpose of the present study was to investigate ankle dorsiflexion SA in people with MS and its relationship to functional performance. RESEARCH QUESTION: Is their a difference in dorsiflexion SA in MS participants compared to healthy individuals and does it impact functional performance? METHODS: 13 MS participants (EDSS 3.5 + 1.8) and 13 age matched NON-MS participants underwent maximal isometric (MVC) dynamometry testing for ankle dorsiflexion in both limbs to determine SA. Participants performed three functional tasks of walking performance. RESULTS: There was a significant intra-limb MVC difference in the MS group, and significantly greater isometric SA (p < 0.007) and isokinetic SA (p < 0.04) in the MS group compared to healthy individuals. The MS group exhibited significant correlations between outcomes of functional walking performance with isokinetic but not isometric SA. There was no significant correlation between disability status and functional task performance. SIGNIFICANCE: Ankle dorsiflexion SA is negatively correlated with functional performance in MS participants. MS disability status was not a predictor of functional task performance, and symptom testing may be appropriate to assess walking ability in persons with MS.

Relationship between soleus H-reflex asymmetry and postural control in multiple sclerosis.

BACKGROUND: Impaired postural control is a common symptom in people with multiple sclerosis. Multiple sclerosis frequently presents with asymmetric motor involvement. One measurement yet to be evaluated for asymmetry in people with multiple sclerosis is the soleus Hoffmann reflex. PURPOSE: To measure the soleus Hoffmann reflex between limbs and correlate reflex asymmetry with postural control. MATERIAL AND METHODS: 16 participants completed four sessions of Hoffmann reflex testing and one session of balance testing. RESULTS: Multiple sclerosis participants had significantly greater reflex asymmetry (p = 0.01). The multiple sclerosis group had a significantly lower overall sensory organization testing composite score (p < 0.05), indicating sensory interpretation conflict that resulted in greater postural instability. Multiple sclerosis participants produced a significantly shorter endpoint and maximum excursion (p < 0.01) during limits of stability testing. Hoffmann reflex asymmetry was negatively related to forward endpoint excursion (p < 0.05), maximum excursion (p ≤ 0.01). CONCLUSIONS: Multiple sclerosis participants had greater soleus Hoffmann reflex asymmetry, which appears to significantly influence forward postural control.Implications for rehabilitationSoleus Hoffmann reflex asymmetry appears to influence postural stability.The soleus Hoffmann reflex is capable of adapting to different modes of exercise; therefore, to reduce H-reflex asymmetry it is recommended to individualize physical rehabilitative programming.Assessing the soleus Hoffmann reflex in people with multiple sclerosis during health screenings could be of use to clinical and rehabilitative practitioners.