Adjunctive hiking bouts during 8 weeks regular sailing training improves cardiorespiratory and muscular responses during hiking emulation in highly trained sailors.

To investigate the effects of 8-week hiking bench training on cardiorespiratory and muscular responses of highly trained sailors during hiking emulation. Twenty-four sailors were assigned into two groups: the hiking bench training group (HTG, n = 12) and the control group (CG, n = 12). Both groups maintained their regular training with the HTG performed two additional hiking bench training sessions per week for 8 weeks, while the CG performed an equivalent duration of on-water sailing training. Physiological responses were assessed by performing four successive 3-min hiking bouts on a sailing emulation ergometer before and after the 8-week training period. Comparing the pretest, both groups exhibited a significant decrease (p < 0.05) in the percentage of maximal oxygen uptake (%VO2max) and maximal heart rate (%HRmax); the HTG experienced a greater decrease in %VO2max in bouts 2 and 3. The root mean square (RMS) of rectus femoris (RF), vastus lateralis (VL), rectus abdominis (RA), and external oblique decreased significantly (p < 0.05), whereas the mean power frequency (MPF) of RF, VL, and RA exhibited an increasing trend. The RMS of RF and RA in HTG were lower than those in CG in the initial three bouts; VL and EA in HTG were lower than those in CG in bouts 1 and 2 (p < 0.05). The MPF of RA in HTG was significantly increased in bouts 2, 3, and 4 (p < 0.05). Eight-week hiking bench training could improve hiking economy and the activation of lower limb and trunk muscles delaying the onset of fatigue in sailors.

Anthropometric and physiological profiles of highly trained sailors in various positions and levels.

This study aimed to analyze anthropometric and physiological profiles of highly trained sailors and the differences between sailors regarding various training levels. Forty-two sailors (22 male, 22.4 ± 3.8 years; 20 females, 21.3 ± 3.6 years) were divided into helmsmen and crew groups, and the high- and low-level were distinguished. Sailors completed height, sitting height, legs length, weight, BMI, VO2max, 30 s all-out sprint, isometric mid-thigh pull (IMTP), countermovement jump, bench pull, core endurance tests. The results showed the crew had higher height, sitting height, weight, VO2max and lower trunk flexor endurance test times compared to the helmsmen (p < 0.05). The helmsmen had higher relative peak power/force in the 30 s all-out sprint and IMTP tests compared to the crew, whereas the crew had better absolute strength in bench pull, with significant differences between female sailors (p < 0.05). The high-level sailors showed more sailing experience than low-level sailors (p < 0.05). In conclusion, highly trained crew tend to be taller and heavier, while helmsmen have better trunk flexor endurance. For female sailors, helmsmen have better lower-body power and strength and crew have better upper-body strength. Sailing experience is a reliable variable to distinguish sailors' levels. The specific anthropometric and physiological profiles of sailors in various positions can assist sailing coaches in athlete selection and intervention training.

Kinematic and electromyography characteristics of performing butterfly stroke with different swimming speeds in flow environment.

Objective: To investigate effect of flow speeds on the upper limb muscular activity of butterfly swimmers training in a flow environment. A comparison of kinematic characteristics and muscular activity of upper limbs were made when the swimmers training with different flow speeds in a swimming flume. The purpose was to provide a basis for scientifically formulating special swimming training advice for athletes' training in flow environment. Methods: Ten youth female butterfly swimmers participated in the study with the speed of 70%, 80%, and 90% level of their max speeds. A stroke cycle was divided into four phases (entry, pull, push, and recovery). The kinematic parameters of upper limbs (stroke rate, stroke length, duration of each phase in a stroke cycle) and muscular activity (onset timing, integrated electromyography (iEMG), contribution ratio) of four muscles (Biceps brachii (BB), Triceps brachii (TB), Pectoralis major (PM), and Latissimus dorsi (LD)) were collected and analyzed in different stroke phases. Results: There was no significant difference between stroke rate and stroke length with different flow speeds. There were significant differences among the duration of the four stroke phases. The entry phase had the longest duration, the pull phase had the shortest duration, the push phase was longer than the recovery phase, and the recovery phase was shorter than the entry phase. The BB and PM were activated significantly earlier at 90% of target speed than at 80% of target speed, while the TB was activated significantly later than other two speeds. The muscular contribution ratio of the PM was highest in the pull phase and lowest in the pushing phase. The muscular contribution ratio of the BB was significantly lower in the pushing phase than in other three stroke phases. The muscular contribution of the TB was significantly higher in the recovery phase than in other three stroke phases. The muscular contribution ratio of the LD was highest in the pushing phase, and it was significantly higher in pushing phase and recovery phase than in pull phase. Conclusions: (1) When butterfly athletes training with 70%, 80% and 90% of their max speed in a flow environment, it didn't make significant differences between the kinematic or muscle activation characteristics of the upper limbs movement except the muscle onset timing. (2) Stroke phase was the main factor of the duration and the muscle contribution ratio during butterfly arm stroke for young athletes.

Analysis on the characteristics and relationships of lower limbs strength and power of sailors in different positions and levels.

Hikers and trapeze sailors are two main Olympic groups based on their specific role during sail racing. This study was to analyze the characteristics and relationships of lower limbs strength and power of hikers and trapeze sailors with different levels. Forty-five hikers and trapeze sailors were divided into high-level and low-level groups, respectively. The isokinetic dynamometer was used to measure sailors' lower limbs strength. Concentric and eccentric peak torque (PT) were measured for hamstrings and quadriceps at 60°/s, and isometric knee extensions at 45° knee flexion (0° = full extension). The counter movement jump (CMJ) was performed by Kistler to reflect sailors' lower limbs power. The results showed the hikers had higher quadriceps isometric PT, and male hikers had higher concentric and eccentric PT compared to trapeze sailors (p<0.05). For female sailors, the quadriceps' concentric, eccentric and isometric PT of high-level group were higher than low-level group' (p<0.05). The sailors' conventional and functional H/Q ratio ranged from 0.44 to 0.56 and 0.52 to 0.65, respectively. High-level and low-level groups had no difference in CMJ, which was moderately to strongly correlated with the isokinetic strength (r ranging 0.50-0.81, p<0.01). These findings suggest that long-term training can induce specificity in lower limbs strength of sailors. Hikers have better quadriceps isometric strength compared to trapeze sailors. The quadriceps concentric and eccentric PT can be used as parameters to distinguish between high-level and low-level sailors, but CMJ cannot.

Analysis of sailing variables and performance of laser sailors with different rankings under the condition of certain wind speed.

Objective: The aims of this study were to describe the characteristics of sailing variables and differences between different ranking sailors under the condition of certain wind speed, and predict the variables that affect performance. Methods: Five regatta's data of the 2019-2020 Hempel World Cup Series and Tokyo 2020 Olympic Games for a total of 63 races were analyzed in this study. The wind speed was defined as light wind below 8 knots, medium wind at 8-12 knots and strong wind above 12 knots. Sailors were divided into top 10 and other ranked groups based on their performance for each race. Results: 1) The race time of Laser class was about 50 min. The sailing distance traveled, VMG, percentage of upwind time, and the number of downwind maneuvers increased with an increase in the wind speed, while upwind maneuvers decreased increasing wind speed. Under the same wind speed, the VMG of reaching legs was the highest, followed by downwind and upwind legs in same wind speed. (2) The top 10 sailors had a high VMG, less race time, upwind/reaching legs' time and distance compared to other ranked sailors in all categories of wind speed (p < 0.05). There was no significant difference in the number of maneuvers among sailors of different rankings (p > 0.05). (3) There was a moderate to high correlation between first upwind mark position of sailors and the race ranking (r ranging 0.762-0.851, p < 0.01), and the top 10 sailors' first upwind ranking was close to the race performance. Conclusions: Wind speeds affect sailing variables and race characteristics. VMG and time and distance in upwind and reaching legs are important variables for differentiating sailors' level. Regardless of the wind speed, the first upwind mark position of sailors can be used as an effective factor in predicting the performance of the race.

City Brand Image Building and Its Impact on the Psychological Capital of New Entrepreneurs Following Cultural Construction.

The purpose of the study is to provide effective direction and ideas for urban modernization and promote the development of the city innovation economy and the stability of the employment rate. First, the main contents and influencing factors of urban culture construction are introduced. Second, the construction of city cultural images and the social capital of new entrepreneurs are discussed, and the relationship between the two is analyzed. Then, Interpretative Structural Modeling Method (ISM) is put forward, and five influencing factors of city entrepreneurial environments are expounded. A questionnaire survey is designed based on the ISM model, and a nationwide survey of new entrepreneurs is carried out. The survey results show that entrepreneurs of different genders, ages, and educational levels have different degrees of concern for the city image. Among them, the entrepreneurs with different educational levels have the most obvious difference in their attention to the cultural image of the city (p < 0.05). In addition, public transportation, educational conditions, tourism resources, air quality, and image orientation are the most obvious factors affecting the construction of city brand images (p < 0.05). The influence of the educational level of residents and investment environment on new entrepreneurs is more prominent. This shows that in the process of shaping the city brand image, the improvement of city culture is helpful for new enterprises. The more perfect the city culture is, the more attractive it will be for highly educated entrepreneurs. The study can help relevant decision-makers to plan the future development direction of the city more accurately and realize the stable development of city brand images.

The Internal Connection Analysis of Information Sharing and Investment Performance in the Venture Capital Network Community.

In order to explore the internal connection between information sharing and investment performance in the venture capital network community, this study took environmental-governance start-ups as the research object and used the 2009-2020 environmental-social enterprise start-up venture capital investment events as a data sample. The successful exit rate of the venture capital portfolio and the successful listing rate of investment ventures were used as the measurement criteria. Combined with regression analysis, the relationship between information sharing and investment performance in the venture capital network community was analyzed in detail. Research shows that there are differences between the ways of information sharing in the venture capital network communities. In the regression results, all coefficients are less than 0.01. There is a positive correlation between information sharing and investment performance in the venture capital network community. With the increase in enterprise characteristic variables, the degree of enterprise risk information sharing is getting higher and higher. This ultimately leads to more and more frequent corporate investment performance and a higher possibility of acquisition. Among them, the degree of information sharing in the venture capital network community is relatively high, and venture capital companies that are supported by corporate venture capital institutions will benefit even more from listed capital. Not only was the analysis of the relationship between finance and investment in the venture capital network community pointed out in this research, but also the investment development of entrepreneurial enterprises was also provided with feasible suggestions.