title: The relevance of calf muscle metrics and plyometric outcomes for athletic sprint performance

authors: Williams, Rachel

subjects: athlete testing

abstract: Introduction 
Sprinting is a key performance marker in sports and involves the stretch-shortening cycle (SSC) of the lower limbs. The triceps surae or calf muscle complex is shown to be a key contributor to sprinting, but many calf function assessments used in athlete profiling do not fully consider the SSC. Similarly, lower-limb plyometric abilities are important for sprinting, but few studies explore how plyometrics in the horizontal and vertical axes relate to sprint performance. Therefore, we investigated the association between various calf metrics, single-leg plyometric outcomes, and sprint performances to determine which assessment metrics are the most relevant as athletic performance indicators. 

Methods 
Thirty active participants (14 male, 16 female) completed a test battery in two sessions that included 0-40 m maximum sprints; single-leg calf muscle isometric strength, power, and strength-endurance tests; and plyometrics in the vertical and horizontal axes. Sprint outcomes included maximal sprint acceleration (MSA, 0-10 m time), maximal sprint speed (MSS, 30-40 m time), and 0-40 m sprint time. Calf muscle metrics included single-leg seated and standing isometric strength (N), peak concentric power (W) from an eccentric-concentric task with an additional 30% body mass load, and total repetitions and positive work (J) from strength-endurance testing. Plyometric outcomes included vertical reactive strength index (RSI) and jump height (m) from a single-leg 30-cm drop jump, and two horizontal RSIs and total horizontal distance (m) from a forward triple hop for distance. Pearson correlation coefficients (r) were computed to assess the strength of relationships between I sprints, calf, and plyometric measures. Significance was set to p ≤ 0.05. Only significant values are presented in the results. 

Results 
Calf power showed large correlations with MSA (r = -0.678) and MSS (r = -0.707), as did total work during strength-endurance testing (MSA: r = -0.588; MSS: r = -0.578). Standing isometric calf strength was largely correlated to MSS (r = -0.544) and MSA (r = -0.562); whereas seated correlations were moderate (MSS: r = -0.470; MSA: r = -0.459).  
Horizontal total distance (r = -0.785 to -0.694) and horizontal RSIs showed large correlations with MSA, MSS, and 40 m sprint times. Vertical RSI exhibited moderate correlations with MSA, MSS, and 40 m sprint times (r = -0.422 to -0.386). Vertical drop-jump height was not significantly related to any sprint metrics. Plyometric outcomes within the same axes were largely interrelated, with only the vertical RSI exhibiting a moderate relationship to horizontal RSI2 (r = 0.366) and horizontal total distance (r = 0.407). The only large correlation between plyometric and calf metrics was between horizontal total distance and calf power (r = 0.628). Horizontal total distance moderately correlated with all other calf metrics (r = 0.487 to 0.381). Seated isometric strength moderately related to vertical plyometric outcomes (r = 0.411 to 0.447). 

Conclusion 
The calf power test was the most strongly associated calf metric to sprint performances, and horizontal total distance was the most strongly associated plyometric outcome to sprint performances. Both tests are easy to implement in practice and could be used as a maximal sprint acceleration and speed performance indicator. Future research should explore whether a causal relationship exists and explore the relevance of outcomes to high performance sports and rehabilitation.

text: The relevance of calf muscle metrics and plyometric outcomes for athletic sprint performance Introduction 
Sprinting is a key performance marker in sports and involves the stretch-shortening cycle (SSC) of the lower limbs. The triceps surae or calf muscle complex is shown to be a key contributor to sprinting, but many calf function assessments used in athlete profiling do not fully consider the SSC. Similarly, lower-limb plyometric abilities are important for sprinting, but few studies explore how plyometrics in the horizontal and vertical axes relate to sprint performance. Therefore, we investigated the association between various calf metrics, single-leg plyometric outcomes, and sprint performances to determine which assessment metrics are the most relevant as athletic performance indicators. 

Methods 
Thirty active participants (14 male, 16 female) completed a test battery in two sessions that included 0-40 m maximum sprints; single-leg calf muscle isometric strength, power, and strength-endurance tests; and plyometrics in the vertical and horizontal axes. Sprint outcomes included maximal sprint acceleration (MSA, 0-10 m time), maximal sprint speed (MSS, 30-40 m time), and 0-40 m sprint time. Calf muscle metrics included single-leg seated and standing isometric strength (N), peak concentric power (W) from an eccentric-concentric task with an additional 30% body mass load, and total repetitions and positive work (J) from strength-endurance testing. Plyometric outcomes included vertical reactive strength index (RSI) and jump height (m) from a single-leg 30-cm drop jump, and two horizontal RSIs and total horizontal distance (m) from a forward triple hop for distance. Pearson correlation coefficients (r) were computed to assess the strength of relationships between I sprints, calf, and plyometric measures. Significance was set to p ≤ 0.05. Only significant values are presented in the results. 

Results 
Calf power showed large correlations with MSA (r = -0.678) and MSS (r = -0.707), as did total work during strength-endurance testing (MSA: r = -0.588; MSS: r = -0.578). Standing isometric calf strength was largely correlated to MSS (r = -0.544) and MSA (r = -0.562); whereas seated correlations were moderate (MSS: r = -0.470; MSA: r = -0.459).  
Horizontal total distance (r = -0.785 to -0.694) and horizontal RSIs showed large correlations with MSA, MSS, and 40 m sprint times. Vertical RSI exhibited moderate correlations with MSA, MSS, and 40 m sprint times (r = -0.422 to -0.386). Vertical drop-jump height was not significantly related to any sprint metrics. Plyometric outcomes within the same axes were largely interrelated, with only the vertical RSI exhibiting a moderate relationship to horizontal RSI2 (r = 0.366) and horizontal total distance (r = 0.407). The only large correlation between plyometric and calf metrics was between horizontal total distance and calf power (r = 0.628). Horizontal total distance moderately correlated with all other calf metrics (r = 0.487 to 0.381). Seated isometric strength moderately related to vertical plyometric outcomes (r = 0.411 to 0.447). 

Conclusion 
The calf power test was the most strongly associated calf metric to sprint performances, and horizontal total distance was the most strongly associated plyometric outcome to sprint performances. Both tests are easy to implement in practice and could be used as a maximal sprint acceleration and speed performance indicator. Future research should explore whether a causal relationship exists and explore the relevance of outcomes to high performance sports and rehabilitation.

year: 2024

title: Why using the level of the active component in manuka honey to replace the UMF rating is misleading

authors: Molan, Peter C.

subjects: biology

abstract: There have been some news releases claiming that Professor Henle in Germany has found the chemical identity of UMF, and that in future chemical analysis will be used instead of assays of antibacterial activity to indicate the level of UMF in manuka honey. Both of these claims are misleading. Because the level of active substance in manuka honey is an unreliable indication of the level of antibacterial activity and can be very misleading, it is hard to see any commercial advantage for it to be used to indicate antibacterial activity other than if someone wanted to fool the consumer into thinking that the higher numbers are giving them a level of antibacterial activity that is far higher than they are really getting.

text: Why using the level of the active component in manuka honey to replace the UMF rating is misleading There have been some news releases claiming that Professor Henle in Germany has found the chemical identity of UMF, and that in future chemical analysis will be used instead of assays of antibacterial activity to indicate the level of UMF in manuka honey. Both of these claims are misleading. Because the level of active substance in manuka honey is an unreliable indication of the level of antibacterial activity and can be very misleading, it is hard to see any commercial advantage for it to be used to indicate antibacterial activity other than if someone wanted to fool the consumer into thinking that the higher numbers are giving them a level of antibacterial activity that is far higher than they are really getting.

year: 2008

title: Iwi cultural identity: The praxis of tūpuna narrative

authors: Williams, Amelia Amy Tuihana

subjects: Māori

abstract: This research is a narrative-based study of tūpuna narrative practices. As a privileged medium tūpuna narratives construct the conditions of iwi praxis which leads to mana-motuhake: the political independence and self-determination of Māori. This study explores how the Ngāti Koi applied ‘tūpuna narratives’ to challenge the hegemonic identity imposed on them that effectively alienated and silenced them erasing their memories of who they were and are. It is an auto-ethnography of an iwi, a whānau, a family it is a story about the writer. While this may seem a personal objective, the result indicates a cultural problematic in that the search for identity involves a critical kaupapa Māori investigation for an iwi to make sense of the act of colonisation, the colonial institutions that named them and the revitalization of their iwi identity in a Treaty of Waitangi context.  

This study has found that ‘tūpuna narratives’ represent identity conceptions that have implications for traditional normative practices. In narrative study there are no prescribed means for unearthing and creating meanings, research methods take the form of co-construction, the emphasis is on doing what is necessary to capture the lived experiences of iwi in terms of their particular-and-unique circumstances. Over time dominant theories have tended to align narrative practices with journalism, storytelling, myth and legend, tale and fable diminishing its conceptual role as the ‘epistemological other’ of the social sciences. 

The findings of this research illustrate the significant limitations of these theories. Narrative research is considered both a research method ‘in itself’ and also the phenomenon under study. In this study, narrative is applied as a conceptual metaphor to create interpreted descriptions, to understand and link causal historical and personal events to colonial institutional decision-making. Placed within the conceptual constellation of Kaupapa Māori narrative methodology becomes a powerful tool for change: creating the conditions of iwi praxis which is the making, the transformation and revitalisation of iwi cultural identity. 

As I write Hauraki enters a Treaty of Waitangi ‘settled world’ the settlement formulae premised on the falsified stories begat by nineteenth-century institutional decision-makers. These stories have created a legacy of unease as open inter iwi hostilities are unleashed. Treaty settlements should result in rangimarie-peace, justice and praxis for iwi both internal to, and external of its polity and cultural borders. Clearly, they do not and the need for tūpuna narratives, free of colonial-institutional storying, remains.

text: Iwi cultural identity: The praxis of tūpuna narrative This research is a narrative-based study of tūpuna narrative practices. As a privileged medium tūpuna narratives construct the conditions of iwi praxis which leads to mana-motuhake: the political independence and self-determination of Māori. This study explores how the Ngāti Koi applied ‘tūpuna narratives’ to challenge the hegemonic identity imposed on them that effectively alienated and silenced them erasing their memories of who they were and are. It is an auto-ethnography of an iwi, a whānau, a family it is a story about the writer. While this may seem a personal objective, the result indicates a cultural problematic in that the search for identity involves a critical kaupapa Māori investigation for an iwi to make sense of the act of colonisation, the colonial institutions that named them and the revitalization of their iwi identity in a Treaty of Waitangi context.  

This study has found that ‘tūpuna narratives’ represent identity conceptions that have implications for traditional normative practices. In narrative study there are no prescribed means for unearthing and creating meanings, research methods take the form of co-construction, the emphasis is on doing what is necessary to capture the lived experiences of iwi in terms of their particular-and-unique circumstances. Over time dominant theories have tended to align narrative practices with journalism, storytelling, myth and legend, tale and fable diminishing its conceptual role as the ‘epistemological other’ of the social sciences. 

The findings of this research illustrate the significant limitations of these theories. Narrative research is considered both a research method ‘in itself’ and also the phenomenon under study. In this study, narrative is applied as a conceptual metaphor to create interpreted descriptions, to understand and link causal historical and personal events to colonial institutional decision-making. Placed within the conceptual constellation of Kaupapa Māori narrative methodology becomes a powerful tool for change: creating the conditions of iwi praxis which is the making, the transformation and revitalisation of iwi cultural identity. 

As I write Hauraki enters a Treaty of Waitangi ‘settled world’ the settlement formulae premised on the falsified stories begat by nineteenth-century institutional decision-makers. These stories have created a legacy of unease as open inter iwi hostilities are unleashed. Treaty settlements should result in rangimarie-peace, justice and praxis for iwi both internal to, and external of its polity and cultural borders. Clearly, they do not and the need for tūpuna narratives, free of colonial-institutional storying, remains.

year: 2020