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Background. Handball is a fast paced sport, with high velocity movements performed in a predominantly unilateral plane. In order to make training as specific as possible to on court movements, resistance training programmes should involve exercises that reflect the speed and stance of how they will be performed during gameplay however, working velocities are rarely prescribed due to the lack of research in the area. Aim. The aim of this study was (1) to determine the effect of three different training modes; unilateral high velocity (UHV), bilateral high velocity (BHV) and bilateral slow velocity (BSV) on vertical loaded and unloaded jumps, sprint, agility and balance. (2) To determine if any of these interventions had more of an effect when compared to each other. Methods. 29 women from four teams in the Swedish Elitserien participated in a 16-week intervention study. Teams were assigned to either UHV, who performed unilateral exercises with a high intended movement velocity, BHV, bilateral exercises at a high intended movement velocity, or BSV, who continued their regular bilateral slow velocity training. Power was assessed pre- and post-intervention by loaded vertical squat jump and countermovement jump (CMJ) both unilaterally and bilaterally. Performance assessments were conducted through 20m Sprints, agility T-test and Y-balance test. Effect sizes were calculated to determine the magnitude of differences from pre- to post-intervention in three training modes. One-way ANOVA determined if the group interactions were significant. Results. All three training modes increased their power output to varying levels and effect sizes. The UHV group demonstrated large effect sizes for all improvements in power output, whilst the BHV and BSV groups ranged from trivial to large. UHV got significantly faster at reaching time to peak velocity in unilateral and bilateral measures compared to both BHV and BSV (p=<0.05). Conclusion. The results suggest that a 16-week resistance training intervention regardless of stance improves power however to varying magnitudes. The high velocity groups showed greater improvements in measures of power and performance. This study suggests that resistance training at a high intended movement velocity may be beneficial for improving power and performance in elite women’s handball players.

Injury to the anterior cruciate ligament (ACL) may have consequences for an athlete in the form of pain, decreased activity levels and early-onset osteoarthritis. Female athletes are at increased risk of injury, perhaps because of differences in neuromuscular function. Methods of identifying risk factors and effective prevention strategies for ACL injury have traditionally involved athletes of high school age or older. However by that age, the opportune time to intervene may have passed. This thesis involves a sequence of studies which measures the neuromuscular function of younger athletes, aged 10-14 years. First, the reliability of measuring strength and power of the lower extremity on an isokinetic dynamometer was explored. Torque and power of the hip flexors and knee extensors were the only measures with acceptable reliability. Conversely, peak velocity of all the tested hip and knee movements demonstrated acceptable reliability. A high amount of variability was found with all test movements, and so alternate tests should be used if measuring an individual athlete’s ability. From the data collected within the reliability study, a sex comparison was undertaken to determine if neuromuscular power differed at this young age. It was determined that girls and boys between 10 and 14 years of age do not differ in terms of knee or hip movement velocity or power. There is evidence to suggest that sex differences exist by adulthood; further research is required to determine when the disparity becomes apparent. The final project was to determine whether strength training would improve the manner in which young female athletes land from a jump; a common ACL injury mechanism. This randomized controlled trial found no difference between the intervention group who trained their legs, and the control group who trained their arms. However those athletes with the poorest landings appeared to improve their movement pattern regardless of training regime. This thesis contributes to the literature by providing evidence for measurement protocols for young athletes, introducing neuromuscular power instead of strength into the investigation of contributing factors to injury, and by furthering the examination of strength training as an effective component of prevention programs.

It is known that primates are sensitive to the velocity of moving objects. We can also remember velocity information after moving objects disappear. This cognitive faculty has been investigated before, however, the literature on velocity memory to date has been fragmented. For example, velocity memory has been disparately described as a system that controls eye movements and delayed discrimination. Furthermore, velocity memory may have a role in motion extrapolation, i.e. the ability to judge the position of a moving target after it becomes occluded. This thesis provides a unifying account of velocity memory, and uses electroencephalography (EEG) to explore its neural basis. In Chapter 2, the relationship between oculomotor control and motion extrapolation was investigated. Two forms of motion extrapolation task were presented. In the first, participants observed a moving target disappear then reappear further along its path. Reappearance could be at the correct time, too early or too late. Participants discriminated reappearance error with a two-alternative forced choice button press. In the second task, participants saw identical targets travel behind a visible occluder, and they attempted to press a button at the exact time that it reached the other side. Tasks were completed under fixation and free viewing conditions. The accuracy of participant's judgments was reduced by fixation in both tasks. In addition, eye movements were systematically related to behavioural responses, and small eye movements during fixation were affected by occluded motion. These three results imply that common velocity memory and pre-motor systems mediate eye movements and motion extrapolation. In Chapter 3, different types of velocity representation were explored. Another motion extrapolation task was presented, and targets of a particular colour were associated with fast or slow motion. On identical-velocity probe trials, colour still influenced response times. This indicates that long-term colour-velocity associations influence motion extrapolation. In Chapter 4, interference between subsequently encoded velocities was explored. There was robust interference between motion extrapolation and delayed discrimination tasks, suggesting that common processes are involved in both. In Chapter 5, EEG was used to investigate when memory-guided tracking begins during motion extrapolation. This study compared conditions where participants covertly tracked visible and occluded targets. It was found that a specific event related potential (ERP) appeared around 200 ms post occlusion, irrespective of target location or velocity. This component could delineate the onset of memory guided tracking during occlusion. Finally, Chapter 6 presents evidence that a change in alpha band activity is associated with information processing during motion extrapolation tasks. In light of these results, it is concluded that a common velocity memory system is involved a variety of tasks. In the general discussion (Chapter 7), a new account of velocity memory is proposed. It is suggested that a velocity memory reflects persistent synchronization across several velocity sensitive neural populations after stimulus offset. This distributed network is involved in sensory-motor integration, and can remain active without visual input. Theoretical work on eye movements, delayed discrimination and motion extrapolation could benefit from this account of velocity memory.

Introduktion: Hastighetsbaserad styrketräning är en metod där rörelsehastighet används för att styra träning, samt monitorera träningsintensitet och volym. Metoden har vuxit fram som ett komplement till traditionellt procentbaserad styrketräning. Syfte: Syftet med litteraturstudien var att undersöka effekterna mellan olika metoder av hastighetsbaserad styrketräning och dess förhållande till traditionell procentbaserad styrketräning. Metod: En strukturerad litteratursökning genomfördes i de vetenskapliga databaserna PubMed och SPORTDiscus med de primära sökorden; velocity-based training, percentage based training och training effect. En ytterligare sökning genomfördes i referenslistorna bland de artiklar som uppfyllde inklusionskriterierna. Resultat: Litteraturstudien visade att hastighetsbaserad styrketräning medförde liknande styrkeökningar som traditionell procentbaserad styrketräning. Hastighetsbaserad styrketräning medförde större ökningar i hopphöjd jämfört med traditionell procentbaserad styrketräning. Ingen av interventionerna medförde träningseffekter på sprintförmåga. Konklusion: Hastighetsbaserad styrketräning verkar vara lika effektivt för att utveckla maximal styrka men effektivare för att utveckla hoppförmåga jämfört med traditionellt procentbaserad styrketräning. Hastighetsbaserad styrketräning med lägre procentuell hastighetsförlust verkar vara fördelaktigt för att utveckla hoppförmåga medan högre procentuell hastighetsförlust verkar vara fördelaktigt för att utveckla muskelhypertrofi. / Introduction: Velocity based training refers to a method where movement velocity is used to regulate strength training and monitor training intensity and volume. In addition, velocity based training could be considered as a complementary method to traditional percentage based training. Purpose: The aim of the literature review was to investigate the effects of different velocity based training methods and their relationship to traditional percentage based training. Method: A structured literature search was conducted in the scientific databases PubMed and SPORTDiscus with the following search terms; velocity-based training, percentage based training and training effect. A further search was conducted in the reference list among articles that met the inclusion criteria. Results: The literature review shows that velocity based training leads to similar gains in maximal strength as traditional percentage based training. However, velocity based training leads to greater gains in jump height compared to traditional percentage based training. Sprint ability showed no clear outcome following any of the interventions. Conclusion: Velocity based training seems to be just as efficient in developing maximal strength but more efficient in developing explosive strength such as jump height compared to traditional percentage based training. In addition, velocity based training with lower velocity loss thresholds may be more beneficial to improve jump height, whilst higher velocity loss threshold may be more beneficial to develop muscle hypertrophy.